UNIVERSITY   OF   CALIFORNIA 

COLLEGE   OF   AGRICULTURE 

AGRICULTURAL   EXPERIMENT   STATION 

BERKELEY,    CALIFORNIA 


THE  ASPARAGUS  INDUSTRY 
IN  CALIFORNIA 


H.  A.  JONES  AND  W.  W.  ROBBINS 


BULLETIN  446 

January,  1928 


UNIVERSITY  OF  CALIFORNIA  PRINTING  OFFICE 

BERKELEY,  CALIFORNIA 

1928 


THE  ASPARAGUS  INDUSTRY  IN  CALIFORNIA 

H.  A.  JONESi  and  W.  W.  EOBBINS2 


INTRODUCTION 

Asparagus  has  always  ranked  high  as  a  market  garden  and  truck 
crop.  New  Jersey  early  took  the  lead,  and  for  many  years  held  first 
place  in  the  production  of  green  asparagus.  California  became  the 
center  of  the  asparagus  industry  after  the  ravages  in  1896  of  the 
asparagus  rust  in  the  East. 

The  first  attempt  to  can  asparagus  in  this  country  was  made  by 
William  H.  Hudson,  at  Hunter's  Point,  Long  Island,  in  1864.  The 
product  proved  to  be  popular  and  the  industry  grew  in  New  York  and 
New  Jersey.  It  was  not  until  1890  that  the  packing  of  asparagus  in 
California  became  extensive. 

There  has  been  a  marked  increase  in  the  acreage  devoted  to 
asparagus  in  recent  years.  Although  there  is  no  accurate  record 
available  of  the  acreage  in  the  different  states,  it  is  probably  safe  to 
say  that  the  total  acreage  in  the  United  States  has  more  than  doubled 
since  1918. 

There  has  been  a  steady  growth  of  the  asparagus  industry  in 
California  since  its  inception.  The  centers  of  production  have  shifted 
somewhat  until,  today,  the  three  main  districts  are  the  Delta,  the 
Imperial  Valley,  and  the  San  Fernando  Valley. 

This  bulletin  contains  material  which  will  be  of  use  to  the  farmer 
who  is  growing  asparagus  for  the  first  time ;  it  also  gives  the  results 
of  recent  experiments  and  observations  conducted  by  the  California 
Agricultural  Experiment  Station;  and  it  summarizes  data  published 
by  other  investigators  which  may  be  of  application  to  California 
conditions. 

Botanical  Relationships  and  Geographical  Distribution. — Asparagus 
is  a  member  of  the  lily  family  (Liliaceae).  A  number  of  the  repre- 
sentatives of  the  lily  family  are  cultivated  as  vegetables,  the  principal 
ones  being  onions  and  asparagus.  The  only  species  of  asparagus 
which  has  been  cultivated  extensively  in  the  United  States  as  a  food 
plant  is  Asparagus  officinalis. 

A  striking  characteristic  of  the  genus  Asparagus  is  the  slender 
green  branches,  which  usually  occur  in  clusters,  and  from  the  axils 


1  Associate  Professor  of  Truck  Crops  and  Plant  Breeder  in  the  Experiment 
Station. 

2  Associate  Professor  of  Botany  and  Botanist  in  the  Experiment  Station. 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

of  which  the  flowers  arise.  These  slender  branches  are  known  as 
cladodes  or  cladophylls.  The  true  leaves  are  either  scale-like  struc- 
tures as  in  A.  officinalis,  or  spine-like  as  in  many  of  the  tropical, 
ornamental  species. 

All  species  of  Asparagus  may  be  propagated  by  division  of  the 
rootstocks. 

Of  the  common  species  of  Asparagus,  A.  officinalis  is  the  only  one 
which  grows  erect  and  produces  edible  shoots.  Other  common  species 
are  climbing  or  drooping  in  their  habit.  Moreover,  in  A.  officinalis, 
the  plants  are  dioecious;  that  is,  male  (staminate)  and  female  (pisti- 
late)  flowers  are  borne  on  different  individual  plants.  In  the  common 
climbing  or  drooping  species  the  flowers  are  perfect,  that  is,  possess 
both  stamens  and  pistils. 

The  genus  Asparagus  is  distributed  from  Siberia  to  South  Africa. 
The  native  home  of  Asparagus  officinalis  is  somewhat  more  limited, 
ranging  from  Great  Britain  through  Europe  to  Central  Asia.  It  is 
commonly  mentioned  as  a  plant  of  the  seashores  and  riverbanks. 

Asparagus  has  escaped  from  cultivation  wherever  it  has  been 
grown.  Although  not  a  native  of  America,  it  early  escaped  from 
gardens  and  flourished  in  the  wild  state. 


THE  SEED,  SEED  GERMINATION,  AND  DEVELOPMENT  OF  THE 
PLANT  THE  FIRST  SEASON 

External  Characters  of  the  Seed. — In  any  lot  of  asparagus  seeds, 
it  will  be  observed  that  there  are  two  distinct  shapes,  as  shown  in 
figure  1.  If  two  seeds  develop  in  a  single  cavity  of  the  berry,  the 
surfaces  which  touch  become  flattened  because  of  pressure.  However, 
if  but  a  single  seed  develops  in  a  seed  cavity,  it  becomes  equally 
rounded  on  all  sides.  There  is  no  reason  to  believe  that  either  one  of 
these  types  of  seed  is  superior  to  the  other. 

There  is  considerable  variation  in  the  weight  of  asparagus  seed 
among  different  varieties.  Seed  obtained  from  different  sources  may 
vary  considerably  in  size  owing  to  different  methods  of  screening. 
The  seed  of  the  Martha  Washington  strain  is  smaller,  and  that  of 
the  Mary  Washington  is  somewhat  larger,  than  the  seed  of  most  other 
varieties. 

There  is  found  a  pronounced  difference  in  the  glossiness  of  the 
seed  coats  of  various  lots  of  seed.  Some  are  shiny  black,  whereas  others 
are  a  dull  color.  It  is  believed  that  dullness  is  due  at  least  in  part  to 
the  age  of  the  seed.  In  different  lots  of  seed,  there  is  considerable 
variation  in  the  amount  of  fruit  wall  (pericarp)  which  is  attached  to 


Bul.  446] 


THE   ASPARAGUS   INDUSTRY    IN    CALIFORNIA 


the  seed.  This  appears  as  a  thin,  white  papery  coating.  Incomplete 
threshing  and  washing  are  responsible  for  the  presence  of  these 
membranes. 


**SI 


& 


a 

:r4 


Fig.  1. — Two  shapes  of  asparagus  seeds  (top  view).  Left,  rounded  seed  from 
loeule  which  bcre  but  this  one  seed ;  right,  seed  flattened  on  one  side,  from  locule 
which  produced  two  seeds.     (From  Bul.  381.) 


..seed  coat 


Fig.  2. — Diagrams  of  asparagus  seeds  showing  position  of  the  embryo. 
A,  section  through  the  seed  showing  the  embryo  in  longitudinal  section.  B,  section 
through  the  seed  showing  the  embryo  in  transverse  section.     (From  Bul.  381.) 


6  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Internal  Structure. — The  asparagus  seed  has  three  essential  parts 
(fig.  2)  :  (1)  the  seed  coat;  (2)  the  embryo  plant  or  germ;  (3)  the 
endosperm  or  reserve  food. 

Figure  3  shows  a  section  of  the  mature  seed  coat.  In  the  develop- 
ment of  the  seed  coat  there  has  been  a  progressive  desiccation  and 
shrinkage  of  the  cells,  with  a  consequent  decrease  in  the  thickness  of 
this  coat,  The  outer  wall  of  the  single,  epidermal  layer  of  cells 
becomes  very  thick,  and  the  lumina  become  almost  completely  filled 


\  endosperm 


Fig.  3. — Section  of  a  portion  of  an  asparagus  seed,  showing  the  seed  coat 
and  the  large  cells  of  the  endosperm,  with  thick  walls  of  hemicellulose  ("reserve 
cellulose"),  and  cell  cavities  filled  with  oil  globules  and  protein  granules. 
(Treated  18  hours  with  2  per  cent  sodium  hydroxide  solution  in  order  to  swell 
the  cells  of  the  seed  coat.)     Illustration  from  Bui.  381. 


with  a  dark,  brown  granular  material.  Beneath  this  epidermal  layer 
are  the  very  much  compressed  and  dried  remains  of  integumentary 
cells.  Beneath  these  is  a  suberized  membrane,  separable  into  a  broad 
membrane  and  a  narrow  one  closely  compressed.  These  represent 
respectively  the  "cuticles"  of  the  inner  and  outer  integuments.  This 
double  membrane  plays  a  very  important  part  in  the  absorption 
processes  carried  on  by  the  seed,  preventing,  either  totally  or  in  part, 
the  entrance  of  certain  salts  and  other  substances,  although  it  does 


BUL.  446]  THE   ASPARAGUS   INDUSTRY    IN    CALIFORNIA  7 

not  inhibit  the  movement  of  water  through  it.  The  bulk  of  the  seed 
is  composed  of  endosperm  cells,  which  contain  food  reserves. 

The  embryo  is  a  very  small,  slender  body,  simple  in  structure  and 
somewhat  curved  at  one  end  (fig.  2).  At  one  end  of  the  embryo  is  the 
root  tip.  A  short  distance  behind  the  root  tip  is  a  shallow  depression, 
at  the  base  of  which  is  the  growing  point,  The  remainder  of  the 
embryo,  and  by  far  the  largest  part,  is  an  absorptive  organ.  This 
organ,  the  cotyledon,  remains  in  contact  with  the  endosperm  during 
the  early  stages  of  germination,  absorbs  food  from  the  endosperm  and 
delivers  it  to  the  growing  regions. 

The  embryo  is  completely  surrounded  by  the  endosperm.  Most 
endosperm  cells  have  thick  pitted  walls  of  hemicellulose,  and  lumina 
well  filled  with  fat  globules  and  protein  granules. 

The  hard,  flinty  endosperm  constitutes  a  reserve  food  supply. 
There  are  two  chief  kinds  of  food  stored  in  the  endosperm  of 
asparagus.  These  are  hemicellulose  and  fat.  Protein  is  relatively 
less  abundant  as  a  storage  product.  Hemicellulose  is  a  carbohydrate 
somewhat  resembling  starch  and  ordinary  cellulose  in  its  chemical 
composition.  Hemicellulose  is  stored  in  the  walls  of  the  endosperm 
cells ;  fat  occurs  as  droplets  in  the  cell  cavities.  The  hardness  of  the 
endosperm  of  the  asparagus  seed  is  due  to  hemicellulose  in  its  walls. 

Seed  Storage. — There  are  many  conditions  which  affect  the  vitality 
of  seeds.  In  a  ripe  seed,  the  essential  part,  the  living  embryo,  or 
young  plant  is  in  a  relatively  inactive  state.  The  conditions  under 
which  seeds  are  stored  should  be  such  as  to  keep  it  inactive.  The 
temperature  should  be  kept  fairly  low  and  uniform,  and  the  atmos- 
pheric humidity  low.  If  seeds  are  not  stored  in  a  dry  place,  the 
moisture  present  may  be  sufficient,  provided  there  is  the  proper  tem- 
perature and  oxygen  supply,  to  start  germination.  If  germination 
processes  are  started,  it  follows  that  the  respiration  rate  increases, 
with  a  consequent  loss  of  dry  weight  and  a  decrease  in  the  amount  of 
stored  food  and  therefore  of  stored  energy  in  the  seeds.  Seeds  stored 
in  bulk  under  such  conditions  may  "heat."  This  may  be  due  in  part 
to  heat  liberated  by  the  respiration  of  the  seeds  themselves  and  in 
part  to  the  heat  of  respiration  of  fungi  and  bacteria  growing  on  the 
seeds.  The  heat  thus  developed  may  become  so  intense  as  actually  to 
kill  the  embryos.  Under  the  best  storage  conditions,  asparagus  seed 
should  remain  viable  for  a  period  of  from  five  to  seven  years.  It  is 
always  best  to  make  a  germination  test  on  asparagus  seed  before 
planting  to  determine  the  percentage  of  viable  seeds,  so  that  the 
seeding  rate  can  be  accurately  ascertained. 


8  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Conditions  Necessary  for  Germination. — The  requirements  for  the 
germination  of  asparagus  seed,  and  in  fact  of  all  seeds,  are  water, 
oxygen,  and  a  proper  temperature.  In  certain  experiments,  asparagus 
seeds  have  been  kept  in  water  for  three  months  without  showing 
evidence  of  germination,  and  this  prolonged  soaking  in  water  at 
ordinary  temperatures  does  no  apparent  injury  to  the  seeds,  for  when 
they  are  removed  from  the  water  and  placed  under  conditions  suitable 
for  germination,  sprouts  appear  within  a  few  days  and  the  percentage 
of  germination  is  normal.  Asparagus  seeds  submerged  in  water  are 
under  a  condition  of  low  oxygen  supply,  but  they  may  be  made  to 
germinate  within  four  or  five  days  if  the  water  is  aerated  by  bubbling 
air  through  it.  The  above  experiments  point  to  the  conclusion  that 
asparagus  seed  will  endure  long  soaking  in  water  at  ordinary  tem- 
peratures. However,  germination  of  the  seed  will  not  result  unless 
there  is  a  plentiful  supply  of  oxygen,  such  as  occurs  in  a  soil  in  good 
physical  condition. 

The  optimum  temperature  for  the  germination  of  asparagus  seed 
is  between  77°  and  86°  F.  At  68°  F,  germination  is  very  slow. 
Germination  of  asparagus  seed  will  be  slow  if  sown  in  a  soil  the 
temperature  of  which  is  68°  F  or  below.  The  absorption  of  water  by 
the  seed  at  temperatures  below  77°  F  is  very  slow. 

Rate  of  Germination. — The  rate  of  germination  of  asparagus  seed 
depends  upon  water  and  oxygen  supply  and  upon  the  soil  tempera- 
ture. With  all  conditions  near  the  optimum,  the  root  breaks  through 
the  seed  coat  within  6  to  8  days  after  planting ;  within  10  or  12  days 
the  first  shoot  appears.  The  time  required  for  the  shoot  to  reach  the 
surface  of  the  soil  depends  not  only  upon  the  supply  of  water  and 
oxygen,  and  upon  the  temperature,  but  also  upon  the  depth  of  plant- 
ing and  texture  of  the  soil.  The  sooner  the  shoot  reaches  the  light, 
becomes  green,  and  begins  to  manufacture  its  own  food,  the  greater 
are  its  chances  of  survival.  If,  however,  the  developing  seedling  must 
struggle  through  an  excessive  depth  of  soil  or  one  in  poor  physical 
condition,  it  may  exhaust  its  food  supply  and  succumb  before  reaching 
the  surface. 

Hastening  the  Germination  of  Asparagus  Seed. — Borthwick(3)  has 
shown  that  it  is  possible  to  hasten  the  germination  of  asparagus  seed 
by  soaking  it  in  water.  Both  laboratory  and  field  data  show  that 
soaked  seeds  germinate  more  quickly  than  unsoaked  seeds,  even  though 
planted  in  cold  soil.  For  practical  purposes,  a  period  of  3  to  5  days' 
soaking  at  a  temperature  of  86°  to  95°  F  is  recommended. 

The  Germination  Processes  and  Stages  in  the  Development  of  the 
S<<<H'ni<i. — The  first  process  in  the  germination   of  any  seed  is  the 


BuL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  9 

absorption  of  water,  which  softens  the  coats  and  swells  the  seed.  The 
cell  walls  become  filled  with  water,  in  which  condition  they  permit  the 
more  ready  intake  of  oxygen  and  outgo  of  carbon  dioxide.  At  86°  F 
asparagus  seed  absorbs  the  maximum  amount  of  water  (approxi- 
mately 43  per  cent)  in  about  48  hours,  if  immersed.  As  soon  as  the 
contents  of  the  endosperm  cells  are  sufficiently  diluted,  the  various 
enzymes  which  digest  food  are  secreted.  It  will  be  recalled  that  the 
principal  reserve  foods  in  the  endosperm  of  the  asparagus  seed  are 
fat,  protein,  and  hemicellulose.  Gradually,  the  thick  walls  of  hemi- 
cellulose  become  thinner ;  this  material  is  slowly  digested,  that  is, 
changed  to  sugars,  which  are  soluble.  The  proteins  and  fats  are  also 
digested,  and  the  products  of  digestion  are  transferred  to  the  growing 
points  of  the  embryo.  At  these  growing  points,  soluble  foods  are 
being  transformed  into  cellulose  walls  and  into  living  material.  This 
transformation  is  called  assimilation.  All  living  cells  of  the  germi- 
nating seeds  are  respiring.  And  since  the  cells  are  very  active,  the 
process  of  respiration  is  correspondingly  active. 

It  has  been  observed  that  the  embryo  is  completely  surrounded  by 
the  endosperm  (fig.  2).  The  cotyledon  absorbs  food  from  the  sur- 
rounding endosperm  cells  and  transfers  this  food  to  the  growing 
points  of  the  embryo.  As  germination  proceeds,  the  endosperm  cells 
immediately  adjacent  to  the  cotyledon  are  the  first  to  show  indications 
of  disintegration  due  to  the  digestion  of  their  contents  and  walls. 
The  cotyledon  enlarges  (fig.  4),  gradually  encroaching  upon  the 
endosperm,  until  finally  almost  all  of  its  reserve  food  is  absorbed. 
The  developing  embryo,  by  means  of  the  cotyledon,  maintains  con- 
nection with  the  endosperm  for  a  period  of  three  or  four  weeks. 
After  the  young  plant  has  developed  a  primary  root  and  a  leafy 
shoot,  the  cotyledon  and  the  undigested  endosperm  cells,  if  any, 
wither  and  become  disconnected  from  the  seedling.  It  is  possible  to 
observe  on  seedlings  many  weeks  old,  the  scar  marking  the  point 
where  the  cotyledon  was  attached. 

The  root  is  the  first  structure  of  the  embryo  to  break  through  the 
seed  coat  (fig.  4).  Shortly  after  the  root  protrudes,  root  hairs  begin 
to  form  at  a  point  from  2  to  4  millimeters  back  of  the  root  tip.  The 
root  apparently  breaks  its  way  through  the  seed  coat  simply  by 
pressure. 

When  the  primary  root  has  attained  a  length  of  6  to  10  millimeters 
a  "hump"  or  elevation  may  be  observed  just  posterior  to  the  root 
hair  zone  (fig.  4).  Careful  examination  reveals  here  a  slit  or  opening, 
through  which  the  primary  shoot  emerges. 


10 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


In  the  growth  of  the  seedling,  the  single  primary  root  takes  a 
direct  course  downward,  developing  numerous  thread-like  lateral 
rootlets.  Its  chief  function  is  absorption.  It  seldom  attains  a  length 
of  more  than  5  or  6  inches.  It  is  much  more  slender  and  fibrous  than 
the  storage  roots  which   develop   later.      The   single   primary   shoot 


cofy/edon 
an  obsorbing  o/yon 


Fig.  4. — Early  stages  in  the  development  of  the  asparagus  seedling. 
A,  7  days;  B,  10  days;  C,  12  days;  and  D,  18  days  after  planting  of  seed. 

takes  a  direct  course  upward,  and  upon  reaching  the  light  develops 
a  few  side  branches  and  leaves.  The  primary  root  and  primary  shoot 
attain  a  length  of  3  or  4  inches  before  connection  with  the  reserve 
supply  of  food  in  the  seed  is  severed.  The  primary  root  and  the 
primary  shoot  are  temporary  organs.  They  wither  and  die  long 
before  the  end  of  the  first  growing  season. 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


11 


Fig.  5. — Five  stages  in  the  development  of  an  asparagus  seedling.  At  the  left 
a  very  young  stage  showing  the  short  primary  root  and  the  much  shorter  primary 
shoot,  both  of  which  are  attached  to  the  seed  and  are  deriving  nourishment 
from  the  stored  food  in  the  endosperm.  In  the  second  and  third  stages  the 
seed  is  still  attached.  In  the  fourth  stage  the  plant  has  become  independent  of 
stored  food  in  the  seed,  the  primary  shoot  has  branched  slightly,  a  second  shoot 
has  arisen  from  the  crown,  and  a  fleshy  root  has  developed.  In  the  fifth  stage 
there  is  shown  the  primary  shoot,  two  well  developed  secondary  shoots  and 
one  very  short  secondary  shoot.  The  following  are  the  dates  of  digging  and 
the  ages  of  the  different  seedlings:  (1)  April  3,  10  days  after  planting  the  seed; 
(2)  April  7,  14  days  after  planting  the  seed;  (3)  April  27,  34  days  after  planting 
the  seed;  (4)  May  19,  54  days  after  planting  the  seed;  (5)  June  9,  75  days 
after  planting  the  seed.     (From  Bul.  381.) 


12 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  6. — Asparagus  plant  taken  from  the  nursery  August  13,  100  days  after 
planting  the  seed.  Note  the  first  flower-bearing  stalk  (center).  The  primary 
root  has  become  detached  and  the  primary  shoot  has  withered.  This  plant 
shows  very  strikingly  the  increase  in  height  and  diameter  of  the  shoots  as  they 
make  their  appearance  consecutively  throughout  the  season.     (From  Bui.  381.) 


BUL.  446]  TIJE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  13 

Throughout  the  first  season  of  growth  there  is  a  rapid  increase 
in  the  number  of  secondary  shoots. 

Each  new  shoot  which  arises  on  the  crown  during  the  first  year  is 
almost  always  larger  than  the  one  preceding  (figs.  5  and  6).  The 
larger  size  of  the  new  shoots  which  appear  successively  on  the 
lengthening  rootstock  is  probably  due  to  the  rapid  increase  in  the 
supply  of  food. 

The  rate  of  development  of  the  asparagus  plant  in  the  nursery 
depends  much  upon  the  soil  conditions,  particularly  upon  the  avail- 
able water  supply.  Deficiency  in  the  available  water  is  readily 
reflected  in  retarded  growth  of  the  plants.  By  the  last  of  June  the 
roots  have  penetrated  the  soil  to  a  depth  of  7  inches  or  more,  and  by 
the  last  of  July  they  have  reached  levels  as  deep  as  18  inches. 

Sex  Expression  in  the  Nursery. — Under  California  conditions 
asparagus  usually  comes  into  flower  during  the  first  season  of  growth 
from  the  seed.  It  is  often  possible,  however,  even  in  the  nursery 
before  the  flowers  appear,  to  distinguish  male  from  female  plants. 
The  latter  are  taller,  as  a  rule,  than  the  male  plants,  but  the  number 
of  shoots  to  the  plant  may  be  fewer.  Male  plants  bloom  earlier  in 
the  season  than  female  plants.  Considering  the  population  as  a  whole 
early  in  the  season,  the  male  individuals  constitute  a  majority  of  all 
plants  in  bloom. 

THE    ROOTS 

The  Root  System. — As  previously  stated,  the  primary  root  is  a 
temporary  structure.  Within  two  or  three  weeks  after  it  has  protruded 
from  the  seed,  the  first  secondary  root  makes  its  appearance.  It 
originates  at  a  point  on  the  rootstock  at  the  base  of  the  first  secondary 
shoot  (fig.  10).  As  compared  with  the  primary  root,  the  secondary 
ones  are  of  much  greater  diameter.  They  are  fleshy,  cylindrical  roots, 
of  rather  uniform  diameter  throughout  their  entire  length.  They  are 
usually  devoid  of  any  lateral  roots  for  a  considerable  distance  from 
their  tips ;  often  the  first  laterals  are  from  8  to  10  inches  from  the  tip. 
The  lateral  roots,  borne  by  the  thick  fleshy  ones,  are  slender  and 
fibrous. 

It  has  been  customary  to  speak  of  the  large  fleshy  roots  of 
asparagus  as  " storage  roots,"  and  of  the  fibrous  ones  as  "absorptive 
roots. ' '  The  understanding  has  been  that  the  fleshy  roots  are  storage 
organs  exclusively,  whereas  the  fibrous  laterals  arising  from  them 
have  purely  an  absorptive  function.  From  the  description  which 
follows  under  root  structure,  it  will  be  seen  that  the  surface  of  young 
fleshy  roots  is  thickly  covered  with  functioning  root  hairs,  and  hence, 


14 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


mm 


Fig.  7. — Asparagus  plant  showing  top  growth,  crown,  and  mass  of  fleshy 
roots.     Crown  set  in  field,  1919;  photo  taken  July  25,  1924. 


Bul.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  15 

these  roots  serve  not  only  as  storage  but  as  absorptive  organs  as  well. 
The  fibrous  roots,  on  the  other  hand,  appear  to  be  almost  exclusively 
absorptive  structures. 

The  root  system  of  asparagus  has  the  general  form  of  a  cone,  with 
the  apex  toward  the  ground  line  (fig.  7).  Numerous  roots  take  a 
rather  direct  course  downward,  though  the  more  usual  direction  is 
obliquely  downward.  However,  a  great  number  of  the  long,  fleshy 
roots,  particularly  those  arising  from  the  older  and  more  deep-seated 
part  of  the  rootstock,  may  take  an  almost  horizontal  course  in  the  soil, 
and  even  trend  upwards  for  a  long  distance. 


^ffip 


Fig.  8. — Tip  of  fleshy  root  of  asparagus.  The  uninjured  tips  of  old  roots 
continue  to  grow  the  succeeding  seasons.  In  this,  parts  of  two  season's  growth 
are  shown.  Note  the  shreds  of  cortex  torn  back  at  the  point  where  new  root 
growth  begins. 

The  fleshy  roots  arise  from  the  lower  surface  of  the  rootstock.  As 
the  branches  of  the  rootstock  grow  in  length,  fleshy  roots  are  being 
continually  formed  near  the  tip.  As  new  aerial  shoots  are  sent  forth, 
associated  with  them  are  new  fleshy  roots.  In  point  of  time,  buds 
precede  in  their  development  the  roots  with  which  they  are  associated. 
Hence,  one  may  always  expect  to  find  the  most  active  roots  at  the 
extremities  of  the  branches  which  make  up  the  rootstock. 

Growth  in  Length  and  Duration  of  Fleshy  Boots. — Fleshy  roots 
continue  to  grow  at  the  tip  for  several  years  unless  the  tips  are 
injured.  The  following  record  is  of  a  typical  fleshy  root  on  a  six- 
year-old  asparagus  crown,  grown  in  a  sandy  loam  soil  at  University 
Farm,  Davis,  California.  The  root  had  a  total  length  of  approxi- 
mately 11  feet.  This  root  showed  three  definite  scars  along  its 
length,  each  indicating  the  point  where  one  year's  growth  ceased  and 
that  of  the  following  year  began.  The  root  was  at  least  four  years 
old,  possibly  older,  but  evidence  of  greater  age  could  not  be  found. 
Successive  years'  growth  may  be  distinguished  by  the  color  and  texture 
of  the  cortex  (fig.  8).  When  growth  of  the  root  tip  is  resumed  in  the 
spring,  the  protective  cortical  tissue  which  covers  the  tip  is  ruptured 
and  its  shredded  margin  remains  for  a  period,  thus  marking  the 


16 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Pig.  5). — A  vigorous  "  Number  1"  asparagus  crown,  taken  during  the  second 
season  of  growth.  Note  the  injured  root  tips,  which  have  made  no  further 
growth.  Root  tips  which  are  uninjured  in  digging  continue  growth.  The  fresh 
white  story ge  roots,  from  which  yrise  numerous  absorbing  roots,  stand  out  in 
contrast  with  the  older  and  darker  storage  roots  which  bear  fewer  absorbing 
roots.  At  points  marked  "a"  in  the  photograph,  there  can  be  seen  the  line  of 
demarcation  between  two  successive  years'  growth  of  a  storage  root.  (From 
Bui.  381.) 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


17 


termination  and  beginning  of  two  successive  years'  growth.  The 
distinction  between  successive  years'  growth  is  not  very  evident  in  the 
older  parts  of  the  root. 

In  the  digging  of  one-year-old  crowns  for  transplanting,  care 
should  be  taken  that  the  fleshy  roots  be  obtained  with  as  little  injury 
to  them  as  possible.  If  the  growing  point  of  a  fleshy  root  is  not 
injured,  it  will  continue  to  elongate  after  planting.  Storage  roots 
that  have  not  been  badly  crushed  or  injured,  even  though  the  tips 
ma}7  have  been  destroyed,  may  develop  an  abundance  of  lateral 
absorptive  roots.  When  these  habits  of  root  growth  are  considered, 
together  with  the  fact  that  the  bulk  of  the  stored  food  in  asparagus 
is  in  the  fleshy  roots,  the  importance  of  preserving  as  many  of  them 
as  possible  in  transplanting  should  be  kept  in  mind. 

Fleshy  and  Fibrous  Roots. — Under  California  conditions  at  least, 
the  individual  fleshy  roots  function  for  a  period  of  at  least  three  years, 
possibly  longer.  The  fibrous  ones,  on  the  other  hand,  function  for  a 
single  season,  and  then  die,  a  new  "crop"  being  developed  each  season. 
These  new  fibrous  roots  may  arise  on  the  older  as  well  as  on  the  younger 
parts  of  the  fleshy  roots.  Loisel,(14)  describing  the  root  system  of 
asparagus  grown  under  the  conditions  prevailing  in  France,  says  that 
as  new  fleshy  roots  are  formed  the  older  ones  die,  so  that  a  plant  is 
always  young;  the  oldest  roots  are  only  three  years.  He  states  that 
the  two-year-old  roots  have  already  lost  in  part  their  vegetative 
function,  and  in  reality  the  one-year-old  roots  are  the  only  ones  that 
supply  the  plant  with  a  large  amount  of  food. 

Extent  of  the  Boot  System. — The  extent  of  the  fleshy  root  system 
of  asparagus  plants  of  different  ages  is  shown  in  table  1.  The  plants 
grew  in  a  peat  soil  typical  of  the  Delta  region  of  California,  An 
effort  was  made  in  digging  to  secure  as  much  of  each  fleshy  root  as 
possible,  but  it  is  estimated  that  fully  one-half  of  the  total  length  of 
fleshy  roots  was  left  in  the  soil.  The  roots  extended  to  a  maximum 
depth  of  7  feet. 

TABLE  l 
Number  and  Total  Length  of  Fleshy  Boots  in  Asparagus 


Age  of 

set  crown, 

years 

Number 
of  roots 

Total  measured 
length  of  roots 

(feet) 

Estimated  total 

length  of  roots 

(feet) 

1 

252 

379 

758 

3 

396 

724 

1,448 

4 

596 

1,399 

2,798 

5 

1,178 

2,060 

4,120 

6 

1,012 

1,707 

3,414 

18 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


It  will  be  seen  from  these  data,  that  the  root  system  of  an 
asparagus  plant,  as  old  as  six  years,  is  very  extensive.  The  depth  to 
which  they  penetrate  is  dependent  to  a  large  degree  upon  the  depth 
of  the  permanent  water  table. 

In  addition  to  absorption,  the  roots  of  asparagus  function  as  con- 
ducting organs,  as  anchorage  organs,  and  in  the  case  of  the  fleshy 
roots,  as  storage  organs.  The  edible  shoots  that  arise  in  spring  are 
probably  made  almost  entirely  from  reserve  food  in  the  fleshy  roots. 


first  secondary 
/shoot 


Fig.  10. — Stages  in  the  development  of  the  seedling.  A,  April  27,  the  young 
plant  is  still  attached  to  the  seed.  The  primary  shoot  and  primary  root  have 
developed,  and  the  beginnings  of  the  first  secondary  root  are  seen  (dotted). 
B,  May  19,  with  primary  shoot  (a),  first  secondary  shoot  (1),  primary  root  and 
first  secondary  root  and  buds.  C,  June  9,  as  seen  in  section.  B,  June  30,  show- 
ing three  secondary  shoots  (1,  2,  3,  4).  E,  diagram  of  D  showing  relative 
positions  of  new  shoots. 


THE    STEMS    AND    LEAVES 

The  Rootstock  (Underground  Stem). — The  body  of  the  rootstock 
of  asparagus  is  a  structure  compounded  of  parts  of  a  number  of 
lateral  shoots  (branches). 

The  progressive  development  of  the  rootstock  is  shown  in  the  series 
of  drawings  (figs.  10  to  12).  In  figure  11,  observe  that  the  main 
direction  of  growth  of  the  rhizome  is  on  the  side  of  the  primary  axis 
opposite  the  point  of  its  attachment  to  the  cotyledon  (absorbing 
organ).  Aerial  shoot  1  arose  as  a  lateral  branch  from  the  base  of  a; 
aerial  shoot  2  as  a  lateral  branch  from  shoot  1 :  from  the  base  of  shoot 


Bul.  446] 


THE    ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


19 


2,  there  were  two  lateral  shoots  developed,  of  which  No.  3  became  an 
aerial  shoot,  and  2a,  a  side  shoot.  A  number  of  the  lateral  buds  which 
arise  at  the  base  of  an  erect  shoot  remain  dormant  for  a  long  or  short 
period.     These  dormant  shoots  or  "buds"  are  evident  on  the  root- 


pnmary 
shoot 


seed  coat- 
primary^  root 


Fig.  11. — Stage  in  the  development  of  the  asparagus  crown  the  first  season 
from  seed.  Note  the  shrivelled  seed  coat.  Shoots  1-8  belong  to  the  main  axis; 
2a-2~b,  and  4a^-4b,  are  lateral  branches. 


stock ;  each  occurs  at  the  base  of  an  aerial  shoot.    A  rootstock  five  or 
six  years  old  may  bear  a  hundred  or  more  dormant  "buds."  (fig.  13) ^ 
Since  each  shoot  is  a  lateral  arising  from  the  base  of  the  preced- 
ing, its  point  of  origin  is  slightly  above  that  of  its  predecessor.    Thus 


20  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

there  is  a  gradual  elevation  of  the  rootstock.  The  rate  of  elevation 
depends  upon  the  original  depth  at  which  the  crown  was  planted. 
For  example,  in  figure  14  is  shown  a  rootstock  all  branches  of  which 
grew  almost  vertical.  The  one-year-old  crown  of  this  plant  was 
planted  at  a  depth  of  about  20  inches.    In  figure  15  there  is  illustrated 


Fig.  12. — Stage  in  the  development  of  the  crown.     August  13. 

a  crown  the  rootstock  of  which  has  grown  upward  at  a  relatively  slow 
rate  from  year  to  year.  This  crown  was  planted  to  the  usual  depth 
of  about  10  inches. 

In  a  very  old  plant  the  upper  part  of  the  rootstock  may  be  exposed 
and  the  new  shoots  may  arise  at  or  very  near  the  soil  surface.    As  the 


Bul.  446  J  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


21 


Fig.  13. — Detail  of  a  lateral  branch  of  asparagus  crown,  which  has  been 
stripped  of  roots.  Note  the  lateral  buds  along  the  full  length  of  the  branch. 
Crown  set  1919;  photo  taken  August  20,  1924. 


Fig.  14. — Asparagus  crowns  showing  the  manner  of  growth  resulting  from 
deep  planting  of  the  crown.  The  crowns  were  planted  at  a  depth  of  18  inches; 
as  a  result  the  branches  grew  almost  vertically  upward.  Crowns  six  years  old. 
The  crown  on  the  left  shows  the  appearance  before  the  roots  were  removed. 


22 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


rootstock  ages,  the  lower  and  oldest  portion  of  it  may  decompose,  so 
that  there  is  a  tendency  for  it  to  become  divided  into  several  distinct 
parts. 

The  rootstock  proper  is  a  woody  structure,  possessing  innumerable 
vascular  strands  which  cross  and  re-cross  each  other.  It  is  mainly  a 
conducting  structure,  only  a  small  amount  of  food  being  stored  therein. 


Fig.  15. — Portion  of  a  crown  of  asparagus,  showing  a  lateral  branch. 
Note  the  tendency  to  grow  toward  the  surface  of  the  ground. 


The  Aerial  Shoots. — The  aerial  shoots  arise  from  the  rootstock. 
These  shoots  when  young  constitute  the  edible  spears  for  which 
asparagus  is  grown. 

The  main  shoots  are  rapidly  growing  structures,  the  rate  of  growth 
depending  chiefly  upon  the  temperature. 

Working ( 26» 27)  has  shown  that  "light  has  little  or  no  immediate 
effect  on  the  growth  rate  of  young  shoots  or  seedlings,  or  the  height 
they  attain  before  branching.  Its  effect  is  chiefly  through  the  food 
stored  from  previous  photosynthesis."  He  further  states  that  "the 
three  external  factors  of  greatest  importance  in  the  growth  rate  of 
the  young  shoot  are  the  temperature,  the  moisture  of  the  soil,  and  the 
salt  balance  of  the  soil." 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


23 


Factors  Influencing  the  Size  of  the  Spear. — The  size  of  the 
harvested  asparagus  shoot  or  spear  depends  upon  the  following : 
(1)  heredity,  (2)  age  of  the  plant,  (3)  sex  of  the  plant,  (4)  j)oint  of 
origin  of  the  shoot  on  the  rootstock,  (5)  food  reserve  in  the  rootstock 
and  fleshy  roots,  (6)  soil  fertility,  and  (7)  moisture. 

Heredity. — There  is  a  fairly  constant  difference  between  certain 
varieties  of  asparagus  as  to  the  average  size  of  the  edible  shoots.  For 
example,  under  similar  growth  conditions  the  Mary  Washington 
variety  usually  produces  spears  that  are  larger  than  that  of  the 
common  varieties  grown  in  this  country.  The  breeding  work  with 
asparagus  has  demonstrated  that  size  of  stalk  is  an  heritable  quality. 


Fig.  16. — Five  different  ages  of  asparagus  crowns  showing  the  growth  made 
each  year.  Photo  taken  July  25,  1924.  Crowns  set  in  field  in  1918,  1919,  1920, 
1921,  and  1923. 

Age  of  Plant. — After  the  tenth  or  eleventh  year,  or  even  earlier, 
there  is,  as  a  rule,  a  noticeable  decrease  in  the  size  of  spears.  It  is  a 
common  observation  that  old  asparagus  beds  produce  "spindling" 
shoots. 

Sex  of  Plant. — Shoots  from  female  plants  are  larger  on  the  average 
than  those  from  male  plants.  This  fact  is  well  shown  by  data 
presented  in  table  3. 

These  data  show  that  male  plants  produce  more  spears  and  a 
greater  total  weight  of  spears  per  crown  than  female  plants.  Male 
plants,  as  compared  with  female  plants,  have  a  tendency  to  produce  a 
larger  number  of  relatively  smaller  shoots. 

Tiedjens(23)  found  that  staminate  plants  have  more  buds  than 
pistillate  plants.     For  example,  for  a  four-year  period,  the  average 


24  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

bud  production  for  the  staminate  plants  was  23,  24,  21,  and  24  respec- 
tively. Teidjens  undoubtedly  refers  to  terminal  buds.  He  points  out 
that  the  majority  of  buds  are  formed  the  season  previous  to  their 
appearance  as  spears,  but  that  in  many  cases  the  first  buds  formed 
during  the  growing  season  may  produce  stalks  the  same  year. 

Point  of  Origin  of  the  Shoot  on  the  Rootstock. — The  largest  shoots 
on  an  asparagus  crown  usually  arise  at  the  extremities  of  the  main 
branches  of  the  rootstock.  The  smaller,  spindling  shoots  arise  from 
lateral  branches  of  the  main  rootstock,  and  usually  appear  near  the 
older  part  of  the  crown.  They  are  frequently  from  buds  that  have 
been  dormant  for  a  number  of  years. 

Food  Reserve  in  the  Crowns. — The  shoots  formed  early  in  the 
season,  at  a  time  when  there  is  a  maximum  food  reserve  in  the  roots, 
are  larger  than  those  which  appear  late  in  the  harvest  season.  This 
decrease  in  size,  as  the  season  progresses,  is  probably  due  at  least  in 
part  to  a  diminishing  food  supply. 

A  study  of  the  composition  of  the  roots  and  rootstock  at  the  begin- 
ning and  at  the  close  of  the  harvest  season  shows  that  the  production 
of  aerial  shoots  is  a  drain  upon  the  food  reserves  in  these  underground 
structures. 

Soil  Fertility. — Size  of  spears,  as  well  as  the  number  of  spears,  is 
influenced  by  the  fertility  of  the  soil. 

Moisture  Supply. — The  asparagus  plant  is  very  responsive  to  the 
supply  of  water.    A  deficiency  of  water  results  in  small  spears. 

Gross  Structure  of  the  Shoot. — The  edible  asparagus  shoot  is  a 
roughly  cylindrical  structure,  usually  slightly  oval  in  cross-section, 
and  bears  a  number  of  leaves  at  the  nodes  (fig.  17).  The  shape  of  the 
tip  of  the  shoot  is  often  mentioned  as  a  variety  characteristic.  A 
lengthwise,  median  section  of  the  tip  shows  a  terminal  growing  point ; 
from  the  nodes  of  this  very  much  shortened  axis  may  be  seen  the 
primordia  of  side  branches,  and  even  of  flowers.  The  tight  tip  is 
desirable  from  the  standpoint  of  the  canner  and  shipper.  By  this  is 
meant  a  tip  in  which  the  scale  leaves  are  closely  compressed  and 
firmly  overlapping,  so  that  no  branch  and  flower  primordia  can  be 
observed.  In  the  open  tip  the  scale  leaves  are  spread  outward,  the 
branch  and  flower  primordia  are  more  or  less  in  evidence,  and  the 
entire  tip  has  an  open  appearance.  It  is  even  possible  in  asparagus 
shoots,  in  which  the  tips  are  open,  to  dissect  the  immature  flowers, 
and  find  the  basal  ones  so  far  advanced  that  their  sex  may  be  deter- 
mined. The  height  at  which  the  branching  begins  is  a  variable 
character.    Some  plants  branch  low,  others  relatively  high.   The  latter 


Bul.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  25 

type  is  more  desirable,  because  the  tip  is  more  tightly  closed,  and 
therefore  a  longer  green  shoot  of  desirable  type  can  be  harvested. 
High  branching  is  characteristic  of  the  Mary  Washington  variety. 
The  tendency  of  the  plant  to  branch  low  or  high  may  be  discerned 
even  in  the  seedling  stage. 

It  appears  from  the  experiments  of  Working(27)  that  temperature 
is  the  chief  external  factor  determining  the  branching  of  young  shoots. 
Neither  light  nor  the  depletion  of  the  reserve  food  material  in  the 


Fig.  17. — An  undesirable   (left),  and  a  desirable  type  of  spear. 

roots  have  any  influence.  In  his  experiments,  shoots  in  the  light 
growing  at  a  temperature  of  95°  to  105°  P  began  to  branch  when 
only  6  to  8  centimeters  long,  whereas  at  a  temperature  of  59°  F  they 
attained  a  height  of  75  to  100  centimeters. 

Cladophylls. — The  needle-like  stems  of  asparagus,  known  as 
1 !  cladophylls, "  are  the  principal  food  manufacturing  organs  of  the 
plant.     They  usually  occur  in  clusters. 

Scale  Leaves. — The  scale  leaves  are  thin,  membranous  structures, 
which  always  arise  at  the  nodes.  They  are  pointed  at  the  tip  and 
bear  a  characteristic  downwardly  directed  lobe. 

The  true  leaves  ("scales")  of  asparagus  constitute  a  very  small 
portion  of  the  plant  surface.    Although  they  may  contain  chlorophyll 


26  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

for  a  time  and  thus  be  capable  of  manufacturing  small  amounts  of 
food,  they  soon  become  dry  and  parchment-like. 

The  chlorophyll  pigment  is  formed  in  the  shoots  shortly  after  they 
appear  above  ground.  A  portion  of  the  food  manufactured  in  the 
green  tissue  of  the  plant  is  utilized  immediately  in  the  growth  of 
shoots.  The  surplus  produced  during  the  growing  season,  however, 
is  stored  in  the  fleshy  roots. 

The  Functions  of  the  Stems. — The  principal  functions  of  the  leaves 
of  most  plants  are  food  manufacture  and  transpiration  (loss  of 
water).  In  asparagus  these  functions  take  place  almost  entirely  in 
the  cladophylls  and  larger  stems.  In  asparagus,  aboveground  stems 
of  all  orders  possess  chlorophyll. 

THE  FLOWERS,   FRUIT,  AND  SEED 

The  Flowers. — The  flowers  occur  in  the  axils  of  scale  leaves  and 
are  associated  with  ordinary  vegetative  branches,  with  " needles' ' 
(cladophylls),  or  with  both.  The  branches  of  the  first,  second,  and 
third  order  usually  have  with  them,  that  is,  arising  from  the  same 
leaf  axil,  two  flowers,  although  there  may  be  none  at  all,  or  as  many 
as  four  or  five  at  the  extremities  of  the  plant.  Clusters  of  needles 
only  may  arise  at  a  node. 

The  flowers  of  asparagus  are  of  the  liliaceous  type ;  they  are 
radially  symmetrical;  the  ovary  is  superior;  the  perianth  lobes  are 
separate;  they  occur  in  two  distinct  whorls  of  three  each,  and  the 
segments  are  similar  in  color  and  texture;  there  are  six  stamens,  in 
two  whorls  of  three  each;  and  there  is  a  single  pistil,  the  ovary  of 
which  has  three  cells  or  locules. 

Asparagus  is  dioecious,  that  is,  has  two  kinds  of  flowers,  staminate 
and  pistillate,  but  only  one  kind  on  a  plant.  Rarely,  perfect  flowers 
occur. 

The  Pistillate  Flower. — The  pistillate  flower  is  smaller  and  is  less 
elongated  than  the  staminate  flower.  These  differences  are  shown  in 
figures  18  and  19. 

There  are  six  rudimentary  stamens.  The  ovary  of  the  pistil  is 
distinctly  three-lobed,  and  in  cross-section  is  seen  to  have  three  locules 
or  ovule  cavities  and  normally  six  ovules  attached  to  a  central  axis. 
The  style  is  short  and  is  more  or  less  distinctly  three-grooved.  The 
stigma  is  three-lobed;  its  surface  is  papillate,  which  enables  it  to 
catch  and  retain  the  pollen  grains. 

There  are  three  stylar  canals  which  extend  from  the  stigma  to  the 
cavity  of  the  ovary.  The  pollen  tubes  grow  along  the  sides  of  these 
canals  and  thus  reach  the  ovules. 


BUL.  446]  THE   ASPARAGUS   INDUSTRY   IN    CALIFORNIA 


27 


Fig.  18. — Stages  in  the  development  of  the  pistillate  (female)  flower  and 
berry,  lettered  in  the  order  of  their  development.  Observe  the  rudimentary 
stamens,     s,  rudimentary  stamen;  p,  pistil. 


28 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 


The  Staminate  Flower. — The  perianth  segments  are  as  described 
in  the  pistillate  flower.  There  are  six  well-developed,  functioning 
stamens.     The  pistil  is  rudimentary  (fig.  19). 

Development  of  the  Flowers. — :The  first  evidence  of  the  flower  is 
a  slight  rounded  protuberance  in  the  axil  of  a  scale  leaf.  The  early 
stages  of  development  of  staminate  and  pistillate  flowers  are  similar. 


Fig.  19.— Stages  in  the  development  of  the  staminate  (male)  flower.     Observe 
the  rudimentary  pistil,     s,  stamen;  p,  rudimentary  pistil. 

In  young  staminate  flowers,  the  pistil  may  have  a  shape  typical  of 
that  of  pistillate  flowers  of  the  same  age,  but  it  fails  to  attain  normal 
size ;  the  absence,  or  very  weak  development,  of  the  style  and  stigma 
is  characteristic  of  staminate  flowers ;  it  may  have  locules  in  the  ovary, 
and  ovules  may  begin  development,  but  they  fail  to  reach  maturity. 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


29 


In  young-  pistillate  flowers,  the  stamens  may  develop  as  those  in  the 
staminate  flowers  for  a  time,  but  subsequently  the  anthers  fail  to 
attain  normal  size,  the  filaments  are  short,  and  there  is  a  disintegration 
of  potential  pollen-mother  cells.  This  is  followed  by  a  shrivelling  of 
the  entire  anther. 

The  development  of  the  anthers  presents  no  features  peculiar  to 
asparagus.  The  ovules  arise  from  the  tissue  on  the  central  axis  of 
the  ovary. 

The  pistil  of  the  staminate  flower  varies  somewhat  as  to  the  stage 
of  development  it  attains.  Usually,  it  is  smaller  than  in  a  normal 
pistillate  flower  and  the  style  and  stigma  may  be  absent  or  very  much 
reduced  in  size.  The  ovules  of  staminate  flowers  usually  do  not 
develop  further  than  the  primary  archesporial  stage.  The  integuments 
seldom  attain  a  size  sufficient  to  enclose  the  ovule.  Disorganization 
of  the  ovule  begins  before  the  anther  of  the  same  flower  has  shed  its 
pollen. 

After  fertilization,  changes  take  place  in  all  parts  of  the  ovule 
and  ovary. 

The  Fruit. — The  young,  immature  fruit  is  green  in  color.  As  it 
matures,  it  assumes  a  red  color.  The  mature  fruit  is  spherical.  The 
perianth  segments  and  the  peduncle  adhere  to  its  base.  At  the  tip  is  a 
small  point,  the  remnant  of  the  style.  The  fruit  wall,  the  central 
axis,  and  the  walls  separating  the  locules  (seed  cavities),  are  some- 
what fleshy.  There  are  three  distinct  layers  of  the  ovary  wall;  the 
exocarp,  the  mesocarp,  and  the  endocarp.  The  exocarp  consists  of  a 
single  layer  of  cells,  the  outer  wall  of  which  is  much  thickened.  The 
mesocarp  is  composed  of  many  rows  of  large  cells.  It  is  in  these  that 
the  chloroplasts,  and  later  the  chromoplasts,  occur.  The  endocarp 
contains  several  rows  of  cells,  and  in  the  mature  berry  it  forms  a  thin, 
parchment-like  membrane  which  often  adheres  to  the  seeds. 

The  asparagus  berry  usually  has  three  seed  cavities.  As  a  rule 
two  seeds  begin  to  develop  in  each  cavity  of  the  ovary.  However, 
they  do  not  always  all  reach  maturity.  Fruits  with  different  numbers 
of  seeds  occurred  with  a  frequency  shown  in  table  2. 


Number,  of 

TABLE  2 

Seeds  to  the  Berry 

Number  of  seeds  to  the  berry 

i 

2 

3 

4 

5 

6 

7 

8 

Total 

Number  of  berries 

Per  cent  of  the  total 
number  of  berries 

86 
6,3 

83 
6.1 

185 
13.8 

265 
19.7 

362 

26.8 

365 

27.2 

3 
0.2 

1 

0.1 

1,350 

100 

30  UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 

From  this  it  will  be  seen  that  there  is  approximately  an  equal 
percentage  of  berries  containing  five  or  six  seeds,  respectively,  and 
considering  all  the  classes,  the  total  percentage  of  berries  having 
fewer  than  six  seeds  is  much  greater  (72.7  per  cent)  than  that  having 
six  seeds  to  the  berry  (27.0  per  cent). 

One  frequently  finds  plants  bearing  a  number  of  berries  which 
redden  prematurely,  are  much  undersized,  and  contain  no  viable  seed. 
They  are  conspicuous  on  account  of  their  bright  orange  color  in 
contrast  to  the  green  of  the  normal  immature  berries.  The  pedicel 
has  a  normal  length.  The  ovary  wall  and  partitions  separating  the 
locules  are  fleshy,  and  orange  in  color.  The  ovule  coats  are  only 
partially  developed.  The  orange  color  extends  throughout  all  tissues 
of  the  pericarp,  and  includes  the  partition  walls  and  placentae. 


THE   SEX   OF   ASPARAGUS 

Male  and  Female  Plants. — As  has  been  stated,  in  asparagus  there 
are  two  kinds  of  plants,  as  to  sex :  male  or  staminate  plants  and  female 
or  pistillate  plants.  Normally,  all  the  flowers  on  any  one  plant  are 
staminate  or  pollen-bearing,  or  all  of  them  are  pistillate  or  seed-bear- 
ing. Occasionally,  however,  hermaphroditic  or  perfect  flowers  are 
found.    Such  flowers  bear  both  stamens  and  pistil  that  are  functional. 

Sex  Intergrades. — In  asparagus  the  following  kinds  of  flowers 
have  been  observed :  strongly  pistillate,  weakly  pistillate,  hermaphro- 
ditic, weakly  staminate,  strongly  staminate. 

In  " strongly  pistillate"  flowers,  the  ovary  is  well  developed,  the 
style  is  long,  and  the  stigmatic  surface  plainly  visible;  the  stamens 
are  represented  by  the  merest  traces  of  atrophied  tissue.  In  "weakly 
pistillate"  flowers  the  ovary  is  somewhat  smaller  than  in  the  preced- 
ing case,  the  style  is  short,  and  the  stigmatic  surface  is  not  so  well 
defined ;  the  form  of  the  anthers  may  be  observed,  although  no  pollen 
is  produced  and  the  anthers  soon  wither.  In  hermaphroditic  flowers 
both  pollen-bearing  anthers  and  ovule-bearing  pistils  are  developed. 
Only  a  very  small  percentage  of  true  hermaphroditic  flowers  have 
been  observed  among  the  hundreds  of  flowers  which  have  been 
examined  in  California  asparagus  fields.  In  "weakly  staminate" 
flowers  the  stamens  are  short,  but  functional,  and  the  ovaries  are 
large  and  bear  a  short  style  but  are  not-ovule  bearing.  In  "  strongly 
staminate"  flowers  stamens  are  well  developed  and  normal  in  size, 
the  pollen  grains  are  functional,  but  the  only  evidence  of  the  pistil  is 
a  very  small  conical  body,  without  a  style,  in  the  center  of  the  flower. 


BUL.  446]  THE   ASPARAGUS   INDUSTRY    IN    CALIFORNIA  31 

Sex  Ratio  in  the  Fields. — The  ratio  of  staminate  and  pistillate 
plants  in  commercial  fields  (California)  was  determined  by  walking 
down  the  asparagus  rows  and  recording  the  sex  of  each  consecutive 
plant.  The  data  show  that  there  are  approximately  equal  numbers 
of  staminate  and  pistillate  individuals. 

Expression  of  Sex  of  Seedling  Plants. — In  the  eastern  United 
States  asparagus  plants  seldom  bloom  until  the  second  year  from  seed, 
but  in  California  a  considerable  number  of  plants  flower  the  first  year. 

Field  studies  show  that  there  is  a  tendency  for  staminate  plants  to 
express  their  sex  much  earlier  in  life  than  pistillate  plants.  Many 
plants  do  not  flower  the  first  season,  but  of  those  that  do,  by  far  the 
larger  percentage  is  staminate. 

Comparison  of  Staminate  and  Pistillate  Seedling  Plants. — Each 
new  shoot  which  arises  on  the  crown  during  the  first  year  from  seed 
is  usually  larger  than  the  preceding.  The  first  four  secondary  shoots, 
so  far  as  observed,  were  never  flower-bearing,  but  in  some  few  indi- 
viduals, the  fifth  secondary  shoot  did  produce  flowers.  In  staminate 
plants,  the  first  flower-bearing  shoot  varied  from  the  fifth  to  the 
eleventh  (average,  7.2  for  the  149  plants  observed)  ;  in  pistillate 
plants,  the  first  flower-bearing  shoot  varied  from  the  fifth  to  the 
fourteenth  (average,  8.5  for  the  80  plants  observed).  These  data 
were  taken  from  August  8  to  11.  on  the  Palmetto  variety.  Thus  it  is 
seen  that  the  first  flower-bearing  shoot  usually  appears  earlier  in  the 
life  of  the  staminate  than  in  the  pistillate  plant.  Measurements  taken 
on  the  two  groups  of  plants  show  that  the  average  height  of  the  first 
flower-bearing  shoot  of  staminate  plants  is  47.8  centimeters,  whereas 
the  average  height  of  the  first  flower-bearing  shoot  of  pistillate  plants 
is  62.4  centimeters,  a  difference  in  height  of  14.6  in  favor  of  the 
pistillate  stalks. 

Top  Growth  of  Staminate  and  Pistillate  Plants  the  Year  Crowns 
Are  Set. — In  a  comparison  of  top  growth  made  by  staminate  and 
pistillate  plants  the  year  the  crowns  are  set  it  was  shown  that 
staminate  plants  produce  a  larger  number  of  stalks,  but  that  there 
is  no  significant  difference  between  the  sexes  as  to  average  height  of 
the  stalk  and  the  average  green  weight  of  tops  if  the  berries  are  not 
removed.  The  berries  comprise  a  large  percentage  of  the  weight  of 
the  pistillate  plants,  although  the  weight  of  these  was  not  determined 
separately  the  first  year.  If  the  weight  of  berries  is  subtracted  from 
the  green  weight  of  tops  it  appears  that  the  food-manufacturing 
surface  of  staminate  plants  exceeds  that  of  the  pistillate.  One  might 
expect,  then,  a  greater  quantity"  of  reserve  food  stored  in  crowns  of 


32  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION 

staminate  than  in  those  of  pistillate  plants,  and  that  the  yield  of 
shoots  the  following  season  would  be  higher. 

Yield  of  Spears  from  Staminate  and  Pistillate  Plants. — A  number 
of  workers  have  noted  that  staminate  asparagus  plants  outyield  the 
pistillate.  Among  these  are  Green (11)  who  in  comparing  50  plants 
each  of  staminate  and  pistillate  found  a  gain  of  about  50  per  cent  for 
the  staminate  plants  over  the  pistillate  plants  during  the  whole  season. 
The  yield  of  staminate  as  compared  with  pistillate  plants  was  pro- 
portionately greater  during  the  early  part  of  the  cutting  season  than 
during  the  late.  Tompson,  at  the  Massachusetts  Agricultural  Experi- 
ment Station,  using  the  Washington  strain  of  asparagus,  reports 
experiments  which  show  that  staminate  plants  produce  the  larger 
number  of  spears,  but  that  the  proportion  of  " giant"  asparagus  is 
much  greater  from  the  pistillate  plants.  This  held  consistently  true 
throughout  the  whole  population,  which  was  over  1,000  plants.  In  a 
later  report   Tiedjens(23)    states  that  "Staminate  plants   are  higher 

producing  by  25  per  cent,  and  hold  up  better  from  year  to  year 

Pistillate  plants  produce  a  greater  percentage  of  "A"  (large)  spears." 
B6ttner,(4)  after  pointing  out  the  superiority  of  male  as  compared  with 
female  plants,  states  that  it  is  a  common  observation  that  in  old 
asparagus  beds  the  gaps  that  appear  here  and  there  in  the  rows  are 
due  to  the  death  of  female  plants.  Whereas  in  the  young  plantation 
there  are  equal  numbers  of  staminate  and  pistillate  plants,  in  old 
plantations  there  is  a  predominance  of  staminate  individuals.  He 
describes  a  method,  known  as  the  "Bottner  System,"  whereby  only 
staminate  plants  are  employed  in  the  plantation. 

In  1923,  an  extensive  experiment  was  started  at  the  University 
Farm,  Davis,  California,  the  object  of  which  is  to  test  the  performance 
of  staminate  and  pistillate  plants  over  a  series  of  years.  In  that  year, 
a  large  number  of  pistillate  and  staminate  plants  were  labelled  in  the 
nursery.  The  seed  was  planted  February  28  and  March  8.  By  Sep- 
tember 3,  31  per  cent  of  the  plants  in  the  nursery  had  come  into 
bloom,  and  by  the  end  of  the  season  approximately  58  per  cent  of  the 
plants  had  expressed  their  sex. 

These  staminate  and  pistillate  crowns  were  planted  early  in  1924 
in  separate  rows  in  the  permanent  bed.  The  rows  are  240  feet  long 
and  the  distance  between  rows  7.5  feet.  Staminate  and  pistillate  rows 
were  placed  side  by  side. 

From  this  planting,  a  record  of  the  top  growth  made  in  1924,  1925, 
and  1926,  and  of  spear  production  in  1925  and  1926  are  shown  in 
table  3. 


Bul.  446] 


THE    ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


33 


TABLE  3 

A  Comparison  of  the  Performance  of  Staminate  and  Pistillate 
Asparagus  Plants     (Crowns  set  1924) 


Staminate 

Pistillate 

1. 

Top  growth,  1924: 

Average  number  stalks  per  plant  (Nov.  8) 

8.51 

0.78 

2.98 
55.87 

18.74 

8.40 

2.65 

15.68 

372.75 

23.77 

2555.97 

8.43 

2.90 

5  70 

Average  weight  green  tops  per  crown,  pounds 

(Nov.  8) 

0  74 

2. 

Yield  of  spears,  1925  (Feb.  25-Apr.  1): 

Average  number  spears  per  crown 

1  95 

Average  weight  spears  per  crown,  grams 

42  66 

Average  weight  single  spear,  grams 

21  90 

3. 

Top  growth,  1925: 

Average  number  of  stalks  per  crown  (Oct.  10) 

Average  weight  green  tops  per  crown,  pounds 
(Oct.  10) 

5.14 

2.33*  1.42t 

8.61 

238  78 

4. 

Yield  of  spears,  1926  (Mar.  5-Apr.  25): 

Average  number  spears  per  crown 

Average  weight  spears  per  crown,  grams 

Average  weight  single  spear,  grams 

27  73 

Yield  per  acre,  pounds 

1612  14 

5. 

Top  growth,  1926: 

Average  number  stalks  per  crown  (Oct.  2).... 

4  69* 

Average  weight  green  tops  per  crown,  pounds 

(Oct.  2) 

2  23     1  56 t 

*  With  berries. 


f  Without  berries. 


Thus  far  the  staminate  plants  are  superior  to  pistillate  plants  in 
that  they  produce  a  larger  number  and  a  greater  weight  of  spears. 
Pistillate  plants,  however,  produce  a  greater  proportion  of  large 
spears  than  do  staminate  plants;  that  is,  the  average  weight  of  a 
single  spear  is  greater.  The  food-making  surface  of  the  staminate 
plants,  as  expressed  in  the  weight  of  the  mature  green  tops  con- 
sistently exceeds  that  of  the  pistillate  plants.  If  the  berries,  which 
constitute  approximately  30  per  cent  of  the  green  weight  of  the  plant, 
are  excluded,  the  tops  of  staminate  plants  weigh  only  slightly  less 
than  double  those  of  pistillate  plants.  In  the  case  of  both  pistillate 
and  staminate  plants  there  is  a  close  relationship  between  the  weight 
of  the  top  growth  and  the  yield  of  spears  the  following  season. 

The  question  arises  whether  or  not  the  differences  between  stami- 
nate and  pistillate  plants  will  last  throughout  the  productive  life  of 
the  plantation.  The  tendency  thus  far  expressed  may  be  shown  by 
comparing  1925  and  1926  spear  production  records. 


34  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

A  comparison  of  the  performance  of  staminate  and  pistillate  plants 
during  two  consecutive  years  (1925  and  1926)  shows  that  the  differ- 
ences between  staminate  and  pistillate  plants,  as  expressed  in  1925, 
are  still  greater  in  1926.  The  harvest  in  1927  showed  approximately 
the  same  differences  between  males  and  females  as  in  the  preceding 
year. 

Crown  Selection  on  a  Sex  Basis. — The  results  cited  in  the  fore- 
going paragraphs  immediately  raise  the  question  as  to  the  practica- 
bility of  segregating  the  crowns  at  the  time  of  digging  on  the  basis 
of  their  sex  and  of  planting  staminate  crowns  only.  Under  climatic 
conditions  of  the  asparagus  growing  sections  of  Europe,  and  of  the 
eastern  United  States,  the  plants  do  not  come  into  bloom  until  the 
second  year  from  seed.  It  has  been  thoroughly  established  that  one- 
year  plants  are  much  superior  to  older  ones;  for  this  reason,  growers 
would  be  reluctant  to  allow  the  plants  to  stand  in  the  nursery  until 
the  second  year  in  order  to  afford  them  an  opportunity  to  select  male 
crowns.  B6ttner(4)  (Germany),  writing  in  1921,  describes  what  he 
calls  the  "Bottner  System."  It  is  based  upon  the  recognition  of  the 
superiority  of  male  over  female  plants.  In  order  to  overcome  the 
difficulty  of  weakened  two-year-old  crowns,  he  transplants  one-year 
crowns  to  a  new  bed,  setting  the  plants  about  4  inches  apart  in  rows 
about  12  inches  apart.  The  roots  are  not  crowded  and  the  plants 
remain  vigorous.  This  method  entails  much  extra  labor,  and  according 
to  Bottner,  staminate  crowns  so  selected  cost  double  that  of  unsorted 
crowns.  He  further  states,  however,  that  the  increased  yields  obtained 
over  a  series  of  years  more  than  pay  for  the  difference  in  the  original 
cost  of  crowns. 

As  pointed  out  above,  under  California  conditions  a  large  per- 
centage of  asparagus  plants  bloom  the  first  year  from  seed.  It  is 
possible  to  go  through  the  nurseries  in  the  summer  and  fall  and  pick 
out  staminate  plants.  One  who  is  trained  can  readily  distinguish  male 
and  female  plants  by  the  flower  characters.  It  is  highly  probable  that 
the  operation  of  segregating  the  crowns  on  the  basis  of  their  sex  will 
prove  to  be  entirely  practicable.  Experiments  are  now  under  way  to 
determine  this. 

It  has  been  ascertained  thus  far  that  the  percentage  of  plants 
expressing  their  sex  the  first  year  is  influenced  by  the  spacing  in  the 
nursery.  For  example,  in  1926  at  the  University  Farm,  in  plots 
where  rows  were  2  feet  apart,  the  percentage  of  plants  that  had 
bloomed  by  September  3  was  30  to  40  per  cent  higher  than  in  plots 
the  rows  of  which  were  1  foot  apart.    Undoubtedly  other  factors,  such 


BUL.  446]  THE   ASPARAGUS   INDUSTRY    IN    CALIFORNIA  35 

as  time  of  planting,  available  salts  in  the  soil  and  available  water  also 
influences  the  time  of  flowering.  Experiments  are  now  under  way 
to  ascertain  the  influence  of  these  factors. 


COMPOSITION  OF  THE  ASPARAGUS  PLANT  AND   FERTILIZERS 

Chemical  analyses  of  the  different  organs  of  the  plant  are  of  some 
interest  in  relation  to  the  nutrient  requirements.  Analyses  made  at 
frequent  intervals  throughout  the  life  of  the  plant  show  the  time  and 
rate  of  absorption  of  the  various  elements,  and  the  time  of  translocation 
of  storage  products  both  to  and  from  the  storage  organs.  Analyses  of 
the  edible  part  of  the  plant  also  show  to  a  certain  extent  its  relative 
food  value. 

Composition  of  the  Boots  and  Root  stocks. — Analyses  of  the  roots 
and  rootstocks  of  asparagus  have  been  made  by  several  investigators 
and  at  different  seasons  of  the  year.  In  general,  it  may  be  said  that 
there  is  a  pronounced  exhaustion  of  sugars  in  these  organs,  resulting 
from  the  production  of  spears,  but  that  the  percentage  of  the  other 
constituents  remains  almost  constant. 

Composition  of  the  Edible  Shoots. — There  is  variation  in  the  results 
reported  by  different  workers  as  to  the  composition  of  the  edible 
shoot.  Nothing  is  indicated  as  to  variety,  age  of  bed,  cultural  prac- 
tices, soil,  climate,  and  date  when  samples  were  taken,  all  of  which 
would  undoubtedly  influence  to  some  extent  their  composition. 

Under  Massachusetts  conditions  data  (Morse(16))  show  that  during 
the  progress  of  the  cutting  season  there  is  an  increase  in  the  sugar 
content  of  the  shoots  and  a  decrease  in  the  protein  and  lignin.  It  is 
suggested  that  the  change  in  the  amount  of  sugar  is  due  to  photo- 
synthesis carried  on  by  the  shoot  itself  and  not  to  any  greater  move- 
ment of  sugar  from  the  roots  and  rootstock. 

Asparagus  has  a  high  water  content,  about  92  or  93  per  cent.  The 
fat  content  of  the  edible  shoots  is  about  0.25  per  cent,  the  nitrogenous 
constituents  slightly  less  than  2  per  cent. 

Composition  of  Asparagus  Tops. — Rousseaux  and  Brioux(19) 
report  that,  in  France,  the  dry  matter  in  the  tops  removed  in  late 
autumn  from  the  fields  amounts  to  about  1,400  pounds  per  acre. 
Morse(16)  estimated  that  the  asparagus  tops  contributed  approximately 
1,500  pounds  of  organic  matter  to  the  acre  each  year.  During  the 
ripening  of  the  tops  there  is  a  decrease  in  the  amount  of  sugar  and 
protein.  These  constituents  are  undoubtedly  translocated  to  the  roots 
and  rootstock. 


36 


UNIVERSITY   OF    CALIFORNIA — EXPERIMENT   STATION 


Mineral  Nutrients  Removed  from  the  Soil  by  the  Asparagus 
Crop. — A  number  of  workers  have  computed,  upon  the  basis  of  the 
composition  of  the  plant,  the  mineral  nutrients  removed  per  acre  by 
the  asparagus  crop  (fig.  20).  As  would  be  expected,  there  is  much 
variation  in  these  results. 

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End  of  April  June  24 

End  of  cutting 


November 
Cutting  of  tops 


Fig.  20. — Pounds  of  fertilizer  elements  absorbed  by  asparagus  plant  during 
the  growing  season.     Data  from  Kousseaux  and  Brioux. 

Rousseaux  and  Brioux (36)  studied  five  different  plantations  in 
France ;  their  analyses  show  the  materials  carried  away  by  the  entire 
crop  of  asparagus,  including  the  spears,  tops,  and  berries.  No 
mention  is  made  of  the  age  of  the  beds  from  which  the  samples 
were  collected.  In  the  spears,  nitrogen  and  potash  constitute  the 
largest  proportion  of  the  mineral  elements.  These  elements  usually 
occur  in  large  amounts  in  growing  tips  and  where  cells  are- under- 
going rapid  division.    Considering  the  material  removed  by  the  entire 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  37 

top  growth,  including  both  spears  and  mature  stalks,  the  principal 
fertilizer  constituents  removed  are  nitrogen  and  potash.  It  is  worthy 
of  note  that  of  the  total  amount  of  these  constituents  used  for  the 
entire  top  growth,  a  relatively  small  percentage,  with  the  exception 
of  phosphoric  acid,  is  found  in  the  edible  spears.  The  high  percentage 
of  the  total  phosphoric  acid  which  occurs  in  the  edible  shoots  is  note- 
worthy. The  results  of  Warren  and  Voorhees(25)  in  the  United  States 
are  comparable  with  those  obtained  by  Rousseaux  and  Brioux  in 
Prance. 

The  edible  portion  is  relatively  rich  in  phosphoric  acid,  but  the 
tops  used  much  more  nitrogen,  potash,  and  phosphoric  acid  than  did 
the  edible  spears  that  were  harvested. 

If  the  tops  are  burned  on  the  bed,  the  phosphoric  acid  and  potash 
are  not  removed,  so  that  the  amount  lost  is  not  large. 

Fertilizing  Asparagus. — There  is  a  great  amount  of  conflicting 
data  bearing  upon  the  fertilizing  of  asparagus.  Many  of  the  fertilizer 
tests  and  experiments  have  borne  results  which  one  must  regard  as 
inconclusive.  It  is  almost  impossible  in  our  present  state  of  knowledge, 
to  make  definite  recommendations.  A  practice  which  has  brought 
rewards  in  one  locality  may  be  unsuited  to  another  locality.  In  many 
instances,  however,  the  reasons  for  this  difference  of  response  are  not 
well  understood.  It  is  very  probable  that  the  practices  of  France  and 
the  eastern  United  States  can  be  no  more  than  suggestive  to  the  growers 
in  California,  where  conditions  are  so  different.  On  the  rich  soils  of 
the  Delta,  very  little  increased  production  has  been  obtained  from  the 
fertilizers  that  have  been  tried.  The  Delta  growers,  however,  are  not 
indifferent  to  the  fertilizer  problem.  They  are  interested  in  develop- 
ing fertilizer  practices  which  will  lengthen  the  profitable  life  of  the 
asparagus  bed,  and  will  also  give  an  increased  yield.  In  some  sections, 
especially  the  East,  the  fertilizer  problem  is  probably  the  most  acute 
one  with  which  the  grower  is  confronted. 

Some  Results  of  Fertilizer  Experiments,  and  Fertilizer  Practices. — 
The  experiments  of  Brooks  and  Morse (5)  in  Massachusetts  seem  to 
show  that  on  sandy  soils  moderate  applications  of  chemical  fertilizers 
are  followed  by  as  good  yields  of  asparagus  as  when  manure  in  com- 
bination with  chemical  fertilizers  or  manure  alone  is  used. 

In  Maryland(8)  a  fertilizer  experiment  was  started  in  1905  on  a 
bed  planted  in  1903.  The  soil  is  reported  as  being  "medium  loam  of 
good  fertility."  Results  similar  to  those  of  Brooks  and  Morse (5'  were 
obtained,  with  the  exception  that  heavy  applications  (20  tons  per 
acre)  of  manure  alone  gave  highest  yields,  but  not  the  largest  net 
profit. 


38  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Warren(25)  gives  the  results  of  fertilizer  experiments  in  New  Jersey 
from  1897  to  1906.  There  were  four  plots,  each  one-eighteenth  of  an 
acre  in  size,  which  were  given  the  following  treatments:  Plot  1 
received  an  application  of  barnyard  manure  at  the  rate  of  20  tons 
per  acre  each  fall.  Plot  2  received  an  application  of  complete  fer- 
tilizer every  spring  at  the  rate  of  500  pounds  per  acre.  This  analyzed 
4.5  per  cent  nitrogen,  7.7  per  cent  phosphoric  acid  (available),  and 
13.3  per  cent  potash.  Plot  3  received  the  same  treatment  as  plot  2, 
with  the  addition  of  150  pounds  each  of  ground  bone  and  muriate  of 
potash  each  fall.  Plot  4  received  the  same  treatment  as  plot  3,  with 
the  addition  of  200  pounds  of  nitrate  of  soda,  each  year  after  the 
cutting  season.  In  1905  and  1906  the  application  of  the  complete 
fertilizer  on  plots  2,  3,  and  4  was  doubled,  but  all  other  treatments 
remained  the  same.  The  results  are  similar  to  those  obtained  in 
Massachusetts,  from  which  the  conclusion  is  derived  that  in  a  number 
of  cases  200  pounds  of  nitrate  of  soda  per  acre  gave  as  good  or  even 
slightly  better  yields  than  larger  amounts.  The  plot  receiving  annual 
applications  of  20  tons  of  manure  per  acre  gave  the  largest  yields. 

The  experience  of  most  French  and  German  growers  is  that 
manure  cannot  be  replaced  entirely  by  commercial  fertilizers.  Their 
practices  are  based  upon  experiences  over  long  periods  of  time.  For 
example,  in  the  Yonne  District,  France,  the  growers  usually  apply 
each  year  from  12,320  to  13,200  pounds  of  manure  per  acre,  this  being 
equivalent  to  about  72  pounds  of  nitrogen,  29  pounds  of  phosphoric 
acid,  88  pounds  of  potash,  and  139  pounds  of  lime.  Not  all  of  this 
manure  becomes  available  to  the  plant  the  first  year.  It  is  estimated 
that  approximately  20  per  cent  of  the  nitrogen  becomes  available  the 
first  year,  the  remainder  becoming  available  gradually  during  the 
succeeding  years. 

In  the  Loir-et-Cher  (France),  in  addition  to  a  fall  application  of 
approximately  12  tons  of  stable  manure  to  the  acre,  640  pounds  of 
slag,  180  pounds  of  potassium  chloride,  and  254  pounds  of  gypsum 
are  also  applied.  Instead  of  potassium  chloride,  530  to  570  pounds  of 
common  sylvinite  may  be  used.  The  commercial  fertilizers  are  spread 
in  the  fall  or  in  February  and  turned  under. 

Experiments  in  the  Cote  d'Or,  of  France,  indicate  that  manures 
alone  are  comparatively  too  expensive  and  do  not  produce  the  largest 
crops.  They  seem  to  show  that  it  is  advantageous  to  supply  half  of 
the  needed  material  in  the  form  of  manure  and  one  half  as  commercial 
fertilizers.  Experiments  there  show  that  the  best  results  are  obtained 
when  13,200  pounds  of  manure,  88  pounds  of  potassium  sulfate,  264 


Bul.  446]  THE   ASPARAGUS    INDUSTRY   IN    CALIFORNIA  39 

pounds  of  slag,  and  88  pounds  of  potassium  nitrate  are  applied  per 
acre.  These  fertilizers  are  turned  under  in  the  fall.  In  addition  to 
these  88  to  132  pounds  of  nitrate  of  soda  to  the  acre  are  spread  in 
April  at  the  time  of  hilling.  It  is  further  stated  that  asparagus  grown 
on  land  fertilized  with  both  manure  and  commercial  fertilizers  is  of 
larger  size  than  that  grown  on  land  fertilized  with  manure  alone. 

Rousseaux  and  Brioux(19)  estimate  that  the  edible  sprouts  har- 
vested during  a  60-day  period  use  30  per  cent  of  the  nitrogen,  50  per 
cent  of  the  phosphoric  acid,  22.5  per  cent  of  the  potash,  and  4.7  per 
cent  of  the  lime  of  the  total  amount  absorbed  by  the  crop  during  the 
year.  These  workers  maintain  that  the  plants  must  have  an  abundance 
of  phosphoric  acid  available  at  the  beginning  of  the  growing  season. 
For  phosphoric  acid,  they  recommend  the  use  of  slag  in  sandy  soils 
and  super-phosphate  in  silicious-calcareous  soils,  and  state  that  the 
potash  should  be  applied  in  the  form  of  a  sulfate  rather  than  a 
chloride.  In  this  connection,  it  should  be  noted  that  experiments  in 
the  United  States  show  that  potassium  in  the  form  of  chloride  gives 
better  results  than  when  the  potassium  is  applied  in  any  other  form, 
such  as  the  sulfate  or  wTood  ashes. 

Meyer(15)  (Germany),  basing  his  conclusions  upon  experiments, 
states  that  asparagus  should  receive  applications  both  of  stable 
manure  and  artificial  fertilizers.  He  recommends  stable  manure  the 
first  year  and  artificial  fertilizer  the  second,  continuing  this  alter- 
nation throughout  the  life  of  the  bed.  The  manure  is  applied  at  the 
rate  of  about  5  tons  to  the  acre,  in  rather  deep  furrows.  The  com- 
mercial fertilizer  which  he  claims  has  given  the  best  yields  and  shoots 
of  the  most  superior  quality,  is  a  mixture  of  equal  parts  of  40  per 
cent  potassium  slag,  superphosphate,  and  sodium  nitrate.  This  mix- 
ture is  applied  broadcast  at  the  rate  of  about  300  pounds  to  the  acre ; 
it  is  then  cultivated  into  the  surface  soil. 

Time  of  Application  of  Fertilizers. — The  time  to  apply  fertilizers 
to  asparagus  has  been  much  debated. 

Close (7)  concluded  from  his  experiments  (Delaware)  that  appli- 
cations of  sodium  nitrate  to  asparagus  beds  during  the  cutting  season 
in  order  to  increase  yields  during  the  season  of  application  could  not 
be  recommended. 

Experiments  with  sodium  nitrate  fertilizers  conducted  in  Massa- 
chusetts by  Brooks  and  Morse(5)  bear  out  the  above  conclusion.  They 
found  that  summer  applications  or  divided  spring  and  summer  appli- 
cations of  manure  and  sodium  nitrate  gave  better  results  than  the 
spring  application. 


40  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Meyer (15)  (Germany)  is  emphatic  in  the  statement  that  the  best 
time  to  apply  fertilizers  to  asparagus  is  immediately  following  the 
harvest  season. 

French  experience  seems  to  be  not  altogether  in  harmony  with  that 
expressed  above.  Rousseaux  and  Brioux(19)  (France)  recommend 
that  phosphates  and  manure  be  spread  in  the  winter  and  plowed 
under  together;  that  potash  fertilizers  and  a  part  of  the  nitrate 
should  be  applied  in  March;  that  the  nitrate  should  be  applied  at 
three  different  times :  one-third  in  March,  one-third  at  beginning  of 
the  cutting  season,  and  one-third  late  in  May.  In  the  district  of 
Vauclese,  the  commercial  fertilizers  are  applied  at  hilling  time. 

It  is  recommended  from  experiments  conducted  in  the  Cote  d'Or, 
France,  that  all  the  fertilers,  except  the  nitrate,  be  plowed  under  in 
late  fall,  and  that  the  nitrate  be  spread  in  early  spring  at  the  time  of 
hilling. 

B6ttner(4)  (Germany)  recommends  manuring  just  at  the  close  of 
the  cutting  season  at  the  time  the  mounds  are  leveled,  regardless  of  the 
type  of  manure  that  is  used.  Best  results  are  obtained  by  the  use  of 
compost  spread  between  the  rows  and  covered  with  dirt  obtained  from 
the  ridges.  He  claims  that  manure  applied  immediately  after  the 
cutting  season  will  stimulate  growth  and  benefit  the  following  harvest, 
while  if  applied  in  late  fall  or  winter  the  following  harvest  will  not 
be  benefitted. 

Influence  of  Fertilizers  on  the  Quality  of  the  Shoots. — In  the  Cote 
d'Or  district  of  France,  a  "tasting  commission"  made  a  special  study 
of  the  taste  of  asparagus  as  influenced  by  different  fertilizers  and  other 
conditions.  They  report :  (1)  when  asparagus  is  grown  in  a  naturally 
moist,  non-calcareous  sandy  soil,  where  manure  alone  is  used  as  a 
fertilizer,  the  shoots  lack  taste  and  are  slightly  bitter :  any  application 
of  sodium  chloride  develops  a  sweeter  taste;  (2)  iron  sulfate  and 
gypsum  improve  markedly  the  taste  of  the  shoots;  (3)  nitrogen  gives 
a  better  flavor  to  the  spears  when  added  in  the  inorganic  form  as 
nitrate  of  soda  than  when  added  in  the  organic  form;  (4)  dried  blood 
gives  the  shoots  a  marked  bitter  taste;  (5)  potash  in  the  form  of 
sulfate  makes  more  pronounced  the  peculiar  taste  of  the  asparagus 
spear,  while  kainit  tends  to  reduce  it;  (6)  phosphoric  acid  tends  to 
develop  the  desired  asparagus  taste,  while  a  lack  of  it  produces  a  less 
desirable  taste. 

There  are  probably  other  factors  besides  fertilizers  which  influence 
the  quality  of  asparagus.  In  almost  any  field,  there  are  some  spears 
which   are   decidedly   more   bitter   than   the   average.       It   has  been 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  41 

suggested  that  slow  growth  may  be  responsible  for  this  bitter  flavor. 
Some  growers  state  that  there  is  a  marked  difference  in  the  flavor  of 
asparagus  harvested  at  different  times  of  the  year.  Some  canners 
consider  that  the  best  quality  of  canning  asparagus  is  grown  during 
the  month  of  May.  There  is  need  for  further  careful  study  and 
analysis  of  the  factors  which  influence  the  quality  of  asparagus. 

Asparagus  and  Salt. — Walker(24)  conducted  a  number  of  experi- 
ments in  Arkansas  on  the  use  of  salt  as  a  fertilizer  for  asparagus.  His 
results,  based  upon  a.  single  season's  work,  show  a  difference  of  13.5 
per  cent  in  favor  of  the  salted  areas.  He  states,  also,  that  the  differ- 
ence was  not  confined  to  the  spring  growth  but  that  increased  vigor 
was  evident  throughout  the  summer.  The  salt  was  broadcasted  at 
the  rate  of  1,000  pounds  to  the  acre.  The  asparagus  was  not  cut 
during  the  season  of  application,  but  no  appreciable  effect  upon  the 
growth  of  the  plants  that  season  could  be  seen,  nor  was  there  any 
prevention  of  the  growth  of  weeds.  The  following  year  a  much  heavier 
application  was  given  the  same  part  that  had  received  salt  the  pre- 
ceding season.  Two  pounds  per  square  yard  was  applied  in  two  equal 
applications  at  intervals  of  two  days. 

Walker  is  of  the  opinion  that  salt  is  beneficial  for  the  following 
reasons:  (1)  it  tends  to  bind  or  compact  lighter  soils;  (2)  it  tends  to 
improve  capillarity;  (3)  owing  to  its  power  of  absorbing  water,  it 
tends  to  increase  the  moisture  in  the  soil;  and  (4)  it  keeps  down  weeds. 

The  more  recent  experiments  of  the  Rhode  Island  Experiment 
Station  seem  to  show  that  sodium  "has  little  or  no  direct  manurial 
action,  but  may  influence  the  growth  of  certain  plants  by  the  effect 
of  the  chemical  reaction  of  the  soil. ' ' 

Rudolf  s(20)  experimented  with  top-dressings  of  sodium  chloride,  in 
addition  to  manure.  He  made  applications  upon  two-year-old  and 
eleven-year-old  asparagus  plants.  Applications  of  common  rock  salt 
(Retsof  agricultural  salt)  were  made  at  the  rate  of  150,  300,  and  500 
pounds  per  acre.  Cuttings  of  spears  were  made  the  same  season  that 
salt  was  applied.  After  the  cutting  season  the  stems  of  the  plants 
were  counted  and  the  length  measured  at  intervals  of  from  seven  to 
ten  days.  The  following  spring  the  same  amounts  of  salt  were  again 
applied,  and  the  spears  were  weighed,  counted,  and  graded  for  market 
purposes.  There  was  an  increase  in  the  number  and  weight  of  spears, 
but  these  were  of  a  poorer  grade.  The  number  of  stalks  and  the  total 
length  of  the  plants  increased  regularly  in  all  series,  the  stalks  reach- 
ing their  maximum  height  in  the  middle  of  the  growing  season.  At 
the  last  measurement  taken,  the  average  total  lengths  per  plant  of  the 


42  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

two-year-old  asparagus  plants  on  the  plots  receiving  150,  300,  and 
500  pounds  of  salt  per  acre  were,  respectively,  21.1,  28.6,  and  38.7 
per  cent  higher  than  the  average  lengths  of  plants  on  the  check  lots. 

The  counting  of  the  stalks  was  continued  until  September  6  and 
the  increase  in  the  average  number  for  the  plots  receiving  150,  300, 
and  500  pounds  of  salt  per  acre  was  found  to  be  2.9,  16.2,  and  26.8 
per  cent,  as  compared  with  the  check  plots. 

Asparagus  grown  on  this  soil  seemed  to  be  stimulated  directly  by 
the  salt  applications,  for  weeds  were  kept  down  by  hand  on  all  plots 
throughout  the  growing  season. 

With  solution  cultures,  Working (27)  found  that  young  asparagus 
seedlings  gave  a  better  yield  in  all  plots  where  sodium  was  added 
except  at  the  concentration  of  0.5  molar,  and  with  another  solution 
where  it  was  thought  that  the  large  amount  of  magnesium  caused  the 
lesser  growth.  The  chlorine  did  not  show  the  specific  action  that 
might  have  been  expected  from  fertilizer  work  reported  by  other 
writers.  Working  thinks  that  "it  is  perhaps  the  magnesium  which 
causes  the  shortening  of  the  life  of  the  asparagus  beds  in  the  lower 
islands  of  the  Sacramento  River,  where  brackish  water  is  carried  up 
by  the  tide." 


GROWING    AND    HANDLING    ASPARAGUS    CROWNS 

Growing  Versus  Buying  Crowns. — Commercial  asparagus  growers 
generally  grow  their  own  one-year-old  crowns.  There  are  several 
reasons  for  doing  this:  (1)  It  usually  costs  less  to  grow  crowns  than 
to  buy  them.  This  applies  especially  to  large  acreages  such  as  are 
usual  when  asparagus  is  grown  for  canning  or  as  a  truck  crop. 
(2)  The  grower  has  information  regarding  the  seed.  When  he  pro- 
duces his  own  seed,  he  is  familiar  with  the  variety  and  performance 
of  the  beds  from  which  the  seed  has  been  obtained.  Seed  for  planting 
the  nursery  may  be  obtained  from  reliable  sources,  either  firms  or 
individuals,  who  know  the  principles  of  selection  and  give  special 
attention  to  the  improvement  of  this  crop.  Since  the  yields  from 
asparagus  extend  over  a  period  of  ten  or  twelve  years,  extra  effort 
can  well  be  expended  in  securing  the  best  seed.  Using  cheap  seed  is 
not  economy.  (3)  There  is  opportunity  for  rigorous  crown  selection. 
Even  under  conditions  conducive  to  the  best  crown  development  some 
grading  should  be  made.  Consequently,  it  is  necessary  to  grow  a 
surplus  so  that  there  will  be  a  sufficient  number  of  good  crows  for 
planting.     Some  nurserymen  and  seedmen  sell  only  the  best  crowns, 


BUL.  446]  THE   ASPARAGUS   INDUSTRY    IN    CALIFORNIA  43 

but  as  a  general  rule  very  little  grading  is  done.  (4)  Delayed  plant- 
ing can  be  avoided.  The  best  results  are  obtained,  as  regards 
immediate  growth  and  perfect  stand,  when  the  crowns  are  set  shortly 
after  digging.  (5)  In  California,  climatic  conditions  are  conducive 
to  good  crown  development.  On  account  of  the  long  growing  season 
and  the  large  amount  of  sunshine  prevalent  during  the  spring, 
summer  and  early  fall,  plants  make  a  greater  growth  in  one  season 
in  California  than  in  most  parts  of  the  country.  For  these  reasons 
it  is  deemed  highly  desirable  that  growers  raise  their  own  crowns. 

If  only  a  few  crowns  are  to  be  planted  as  in  the  case  of  the  home 
garden,  it  is  usually  cheaper  to  buy  them  from  a  reliable  nurseryman. 
The  buyer  should  specify  that  only  well  developed  one-year-old 
crowns  will  be  accepted. 

Types  of  Soil. — Good  asparagus  crowns  can  be  grown  on  soils  of 
various  types.  The  best  soils,  however,  for  the  production  of  nursery 
stock  are  well-decomposed  peat,  or  light,  sandy  loam.  These  soils  are 
open  and  porous  and  facilitate  root  penetration  and  elongation.  One 
of  the  most  important  reasons,  however,  for  choosing  light  soils  for 
the  nursery  is  that  crowns  may  be  dug  with  a  minimum  of  injury. 
Excellent  crowns  can  be  produced  on  light  sandy  soils  if  fertilizers 
and  a  sufficient  amount  of  water  are  applied. 

Heavy  soils  can  be  used  for  the  growing  of  crowns ;  to  keep  them 
in  good  physical  condition,  however,  requires  a  great  amount  of  labor. 
They  usually  remain  wet  till  late  spring,  especially  in  regions  of 
heavy  winter  rainfall,  and  they  warm  up  more  slowly  than  in  the 
lighter  soils,  thus  delaying  germination  and  retarding  the  growth  of 
the  plant  after  germination.  Also,  since  heavy  soils  become  packed, 
it  is  difficult  to  dig  the  crowns  without  injuring  many  of  the  root- 
stocks  and  losing  a  large  percentage  of  the  fleshy  roots.  As  these  roots 
contain  the  reserve  food  supply,  their  loss  is  bound  to  weaken  the  early 
growth  of  the  plant. 

Preparation  of  the  Seed  Bed. — Land  that  is  sub-irrigated  should 
be  nearly  level  so  that  uniform  moisture  conditions  can  be  main- 
tained. On  surface  irrigated  land  a  slight  fall  is  necessary.  The 
soil  should  be  comparatively  free  from  clods.  A  fine,  well  pulverized 
seed  bed  permits  the  soil  particles  to  come  into  close  contact  with  the 
seed,  insuring  a  constant  water  supply  and  rapid  germination. 

Seed  Treatment. — Under  average  field  conditions  it  is  usually  from 
two  to  six  weeks  before  the  plants  appear  above  the  ground,  this 
variation  depending  upon  the  temperature  and  moisture  of  the  soil 
and  the  depth  of  planting. 


44  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Methods  have  been  used  to  overcome  difficulties  resulting  from 
slow  seed  germination.  These  are:  (1)  The  sowing  of  quick  germi- 
nating seeds,  such  as  radishes,  with  the  asparagus  seed.  The  radish 
plants  soon  appear  above  the  ground  and  mark  the  rows  so  that  the 
grower  is  better  able  to  cultivate  between  them.  (2)  Soaking  the 
asparagus  seed  in  water. 

The  first  method  is  little  used  and  growers  differ  as  to  the  utility 
of  the  second. 

Borthwick(3'  obtained  good  results  only  when  the  soaked  seed  was 
planted  in  moist  soil.  Contact  with  dry  soil  even  for  a  day  destroyed 
the  effect.  The  temperature  and  time  of  soaking  seed  may  vary  con- 
siderably and  still  give  beneficial  results.  A  temperature  of  86°  F 
for  four  or  five  days  is  recommended.  Soaking  in  water  at  the 
ordinary  temperatures  of  the  air  (70°  to  75°  F)  for  short  periods  of 
time  has  little  effect. 

After  the  seed  is  removed  from  the  water,  it  should  be  spread  out 
thin  on  a  canvas,  stirred  for  a  few  minutes  until  the  water  disappears 
from  the  surface,  and  then  planted  immediately.  The  soaked  seed 
will  be  hard  and  firm,  and  after  drying  for  a  few  minutes,  may  be 
planted  with  a  drill  or  by  hand.  If  the  seed  is  dropped  by  hand 
in  the  furrows,  moist  dirt  should  be  drawn  over  it  and  firmed 
immediately. 

Planting  Season. — Early  planting  of  seed  is  advised  in  order  that 
the  plant  may  have  a  long  growing  season  during  which  to  develop 
a  large  crown.  The  date  of  planting,  however,  must  be  governed 
largely  by  local  and  seasonal  conditions.  On  the  peat  lands  of  the 
Delta  region  of  California,  seed  can  be  sown  in  late  February  or 
March.  In  the  Imperial  Valley  seeding  can  take  place  somewhat 
earlier. 

Methods  of  Planting. — The  seeding  is  usually  done  with  garden 
drills,  and  occasionally  by  hand.  When  large  acreages  are  planted, 
the  drills  are  arranged  in  gangs,  and  two  or  more  rows  are  sown 
simultaneously.  A  number  of  growers  in  recent  years  have  adopted 
the  method  of  sowing  the  seed  in  furrows  3  to  6  inches  wide  in  order 
to  give  the  growing  plants  plenty  of  room  to  develop  and  still  produce 
a  large  number  of  crowns  to  the  acre.  This  method  is  better  than 
planting  too  thick  in  narrow  rows,  but  it  is  unsatisfactory  on  foul 
land,  as  a  great  deal  of  hand  work  is  necessary  to  keep  the  rows  free 
from  weeds. 

Where  surface  irrigation  is  practiced,  the  seed  is  usually  sown  on 
ridges  or  beds,  similar  to  those  used  in  the  growing  of  lettuce.    If  the 


BUL.  446]  THE    ASPARAGUS    INDUSTRY    IN    CALIFORNIA  45 

spring  rainfall  is  plentiful,  the  seed  can  be  sown  on  the  level,  as  the 
plants  will  be  large  enough  for  furrowing  between  the  rows  by  the 
time  irrigation  is  necessary.  It  is  best  to  sow  on  the  level  or  on  lowT 
beds  in  those  regions  where  strong  drying  winds  are  prevalent. 

Rate  of  Seeding. — The  tendency  among  growers  has  been  to  sow 
the  seed  too  thick.  Not  more  than  five  pounds  should  be  planted  to 
the  acre.  Best  results  are  obtained  when  the  rows  are  about  24  to 
30  inches  apart  and  the  plants  3  to  4  inches  apart  in  the  row.  If  the 
seeds  are  dropped  in  groups  of  two  or  more,  fleshy  roots  and  root- 
stocks  become  so  interwoven  that  it  is  difficult  to  separate  them  at 


Fig.  21. — Asparagus  nursery. 

sorting  time.  The  most  expensive  single  operation  in  connection  with 
the  present  method  of  producing  crowns  is  that  of  separating  the 
different  individuals  after  digging.  This  expense  can  be  greatly 
reduced  by  thinner  seeding.  Moreover,  injury  is  often  done  to  the 
crowns  in  separating  them  wrhen  they  are  grown  in  thickly  matted  rows. 

Depth  of  Planting. — The  proper  depth  of  planting  varies  with  the 
type  of  soil.  In  peat  soils  the  seeds  can  be  planted  2%  to  3  inches 
deep.  There  is  little  advantage  in  deep  planting  except  to  keep  the 
seed  in  contact  with  a  permanent  moisture  supply  and  thereby  insure 
quick  germination.  In  sandy  loam  and  light  sandy  soils,  the  seed 
should  be  planted  from  1%  to  2  inches  deep. 

Intercropping. — Companion  planting  and  intercropping  are  often 
practiced  in  the  production  of  nursery  stock.     Good  crowns  can  be 


46  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

grown  in  young  orchards  where  plenty  of  sunlight  is  available,  but 
the  young  asparagus  plants  will  not  do  well  in  the  older  orchards 
where  there  is  too  much  shade.  Some  growers  raise  nursery  stock 
between  the  asparagus  rows  that  have  just  been  set  in  the  permanent 
field.  This  is  undoubtedly  an  undesirable  practice,  especially  from 
the  standpoint  of  the  permanent  bed.  The  seedlings  rob  the  soil  of 
plant  food  that  is  needed  for  the  growth  of  the  transplanted  crowns. 
Moreover,  the  volunteer  crowns  which  remain  after  digging  are  rather 
hard  to  eradicate  for  a  year  or  two. 

Thinning. — It  is  doubtful  whether  thinning  is  practical.  Seeding 
should  be  regulated  so  as  to  get  the  desired  stand  without  thinning. 
The  method  of  plant  development  makes  the  thinning  process  very 
difficult.  This  operation  must  be  performed  before  the  second  aerial 
shoot  appears  and  before  the  development  of  the  fleshy  root  system 
begins.  The  shoot  usually  breaks  off  at  the  crown  when  an  attempt 
is  made  to  pull  the  plant.  If  the  crown  remains  in  the  soil,  shoots 
again  appear  in  a  few  days.  After  the  fleshy  roots  have  once  started 
to  develop,  the  only  way  to  thin  is  to  dig  out  the  crown ;  in  doing  this, 
however,  there  is  danger  of  injuring  adjacent  plants. 

Irrigation. — The  soil  about  the  developing  rootstock  and  fleshy 
roots  must  be  kept  moist  if  the  best  growth  is  to  be  obtained.  The 
fleshy  roots  will  not  elongate  in  dry  soil.  Fleshy  roots  that  have 
started  to  grow  in  moist  soil  stop  increasing  in  length  when  the  soil 
becomes  dry.  Crowns  which  have  a  large  number  of  short,  fleshy 
roots  have  usually  been  subjected  to  periods  of  drought.  Water 
should  not  be  added,  however,  after*  the  early  part  of  September.  If 
the  soil  is  kept  moist,  new  shoots  continue  to  appear  as  long  as  the 
temperatures  are  sufficiently  high  for  growth  to  take  place.  Shoots 
appearing  late  in  the  fall  make  a  considerable  demand  upon  the  stored 
food  in  the  crown. 

Cultivation. — The  manner  of  cultivation  should  vary  with  the  type 
of  soil  and  the  method  of  planting.  In  weedy  fields,  cultivation  is 
often  necessary  before  the  seedlings  appear  above  the  ground.  If 
radish  seed  has  been  drilled  in  with  the  asparagus  seed  the  rows  can 
be  seen  within  three  or  four  days.  Cultivation  may  be  started  as  soon 
as  the  rows  are  visible.  Hand  cultivation  with  a  wheel  hoe  is  usually 
practiced  where  the  rows  are  close  together.  In  the  case  of  surface 
irrigation  it  is  necessary  to  cultivate  the  ground  just  as  soon  after 
each  irrigation  as  the  soil  can  be  worked.  In  case  of  horse  cultivation, 
care  must  be  taken  not  to  injure  the  fleshy  roots  and  rootstocks  by 
plowing  too  deeply  or  too  near  the  row,  especially  late  in  the  season 


BlJL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  47 

after  the  roots  have  spread  through  the  soil  surface.  The  roots  spread 
from  the  rootstock  in  the  shape  of  a  cone.  They  are  nearest  the 
surface  where  they  are  attached  to  the  rootstock. 

Digging  the  Crowns. — Crowns  are  usually  plowed  out  during  the 
late  fall  or  early  winter.  The  tops  should  first  be  cut  with  a  mowing 
machine  and  then  raked  and  burned  so  that  they  will  not  interfere 
with  the  digging  operation.  The  crowns  can  be  turned  out  with  a 
two-horse  moldboard  plow.  Another  implement  that  has  proved  very 
satisfactory  for  loosening  crowns  in  the  nursery  is  a  U-shaped  knife 
that  runs  under  the  mass  of  fleshy  roots  and  straddles  the  row.  The 
knife  at  the  bottom  should  be  at  least  8  inches  wide  with  an  upward 
tilt  toward  the  rear,  so  that  it  will  loosen  the  soil  about  the  crowns 
and  make  it  easier  to  lift  them.  The  latter  method  of  digging  is 
especially  adapted  to  rows  that  are  planted  far  apart,  in  which  case 
a  large  part  of  the  root  system  can  be  saved.  Whenever  possible,  the 
fleshy  roots  should  be  obtained  uninjured.  If  the  growing  point  of 
the  fleshy  root  is  not  injured,  it  will  continue  to  elongate  after 
planting  (fig.  8). 

A  short-handled  six-tined  manure  fork  may  be  used  to  lift  the 
crowns  out  of  the  soil  and  shake  out  the  loose  dirt.  The  crowns  are 
then  thrown  in  windrows  or  small  piles  and  allowed  to  dry  for  an 
hour  or  so  before  they  are  hauled  from  the  field. 

Crown  Storage. — When  hauled  from  the  field,  the  crowns  should 
be  placed  on  a  dry  floor  or  on  well-drained  ground.  The  best  storage 
temperature  is  about  40°  F,  but  they  can  be  stored  for  a  long  period 
at  much  higher  temperatures  if  the  atmosphere  is  dry.  If  the  crowns 
become  moist  from  heating  or  from  rain  or  heavy  fogs,  they  soon 
decay.  Hundreds  of  thousands  of  crowns  are  lost  each  year  because 
of  rotting.  The  fleshy  roots  contain  large  amounts  of  sugar,  which 
is  an  excellent  medium  for  the  growth  of  mold  organisms.  Mold 
spreads  very  rapidly  in  the  presence  of  moisture  and  a  high  tempera- 
ture, such  as  often  exists  when  crowns  are  stored  in  large  piles.  There 
should  be  ample  opportunity  for  air  to  circulate  between  the  crowns. 
If  crowns  must  be  stored  in  large  piles,  it  is  well  to  refork  them  at 
intervals  of  three  to  four  days  to  loosen  the  pile,  thus  facilitating 
aeration  and  thereby  preventing  heating  and  ' '  sweating. ' '  The  plant- 
ing of  crowns  that  have  been  stored  in  large  piles  and  injured  by 
molding  is  one  of  the  most  common  causes  of  poor  stands  in  the  field. 
The  buds  may  be  dead,  even  though  the  fleshy  roots  appear  sound  and 
healthy.  In  more  severe  cases,  both  the  fleshy  roots  and  the  buds 
may  be  dead. 


48  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

The  crowns  should  not  be  stored  where  they  are  subject  to  desic- 
cating winds  for  a  long  period.  Though  crowns  will  stand  a  great 
deal  of  drying,  growth  response  is  much  more  rapid  if  they  are 
not  subjected  to  extreme  desiccation.  The  best  results  are  obtained 
when  the  interval  between  digging  and  planting  is  short. 

Shipping  Crowns. — Crowns  are  often  transported  in  bulk  for  great 
distances  by  auto  truck  and  rail.  If  not  otherwise  protected,  they 
should  be  covered  with  canvas  to  prevent  them  from  getting  wet  or 
from  drying  out.  For  distance  shipments,  asparagus  crowns  should 
be  packed  in  crates  or  in  loosely  woven  burlap  sacks.  Care  should  be 
exercised  that  the  crowns  are  not  packed  so  tightly,  or  to  such  a  depth, 
that  free  circulation  of  air  about  them  is  prevented.  Failure  to  pro- 
vide good  aeration  will  result  in  "heating"  and  molding,  and  extreme 
injury  to  the  buds  and  roots. 

Age  of  Crowns  to  Plant. — It  is  the  experience  of  asparagus  growers 
than  one-year-old  crowns  are  superior  to  older  ones.  B6ttner(4)  (Ger- 
many) calls  attention  to  tests  in  which  one,  two,  and  three-year-old 
crowns  were  planted  in  adjacent  rows  and  the  yields  determined  at 
the  end  of  four  years.  The  yield  from  one-year-old  crowns  was  almost 
double  that  from  two-year-old  crowns,  and  treble  that  from  three- 
year-old  crowns.  If  the  crowns  are  permitted  to  remain  two  years 
in  the  nursery  under  crowded  conditions,  growth  is  checked  and  the 
plants  seem  to  be  very  much  weakened.  Moreover,  on  account  of  the 
intertwining  of  the  roots,  two-year-old  crowns  cannot  be  easily  separ- 
ated without  injuring  many  of  the  roots.  One-year-old  crowns  may 
be  dug  with  less  injury  to  the  roots  and  less  interruption  to  their 
growth. 

Crown  Selection. — Large  acreages  of  asparagus  have  been  planted 
in  years  past  without  selection  of  crowns.  The  experience  of  European 
asparagus  growers  seems  to  have  been  that  it  pays  to  practice  crown 
selection.  With  them,  it  is  a  matter  of  course.  Many  asparagus 
growers  in  this  country,  however,  still  believe  that  rigorous  selection 
is  impracticable. 

At  the  present  time  some  experimental  data  in  support  of  crown 
selection  are  available.  In  the  1916  Annual  Report  of  the  Pennsyl- 
vania State  Agricultural  College,  Myers(17)  reports  the  results  of 
crown  selection  of  two  varieties,  Palmetto  and  Argenteuil.  One-year- 
old  crowns  were  divided  into  three  grades:  No.  1  (the  largest),  No.  2 
(medium),  and  No.  3  (the  smallest).  The  weights  of  the  different 
grades  are  not  given.  The  crowns  were  planted  in  the  spring  of  1908, 
and  asparagus  was  cut  for  the  first  time  in  1910. 


Bul.  446] 


THE    ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


49 


Fig.  22. — Grades  of  crowns:  " Number  1,"  "Number  2,"  and  "Number  3." 
It  should  be  the  aim  of  the  grower  to  produce  ' '  Number  1 ' '  crowns  to  plant  in 
the  permanent  field.      (From  Bul.  381.) 


50  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

There  was  no  striking  difference  between  the  yields  obtained  from 
the  No,  1  and  No.  2  crowns.  In  no  case,  however,  did  the  No.  3's 
produce  as  much  as  the  other  two  grades,  even  after  a  period  of  six 
years. 

Experiments  to  determine  the  relative  value  of  crowns  of  different 
sizes  were  started  in  New  Jersey  in  1924.  The  Atlock  strain  of 
Palmetto  was  used.  Three  grades  of  roots  were  selected,  "firsts," 
"seconds,"  and  "culls."  The  plants  were  raised  in  1923,  and  the 
crowns  transplanted  in  1924. 

In  a  brief  account  of  this  experiment,  the  statement  is  made  that 
"Since  it  is  well  known  that  the  yield  of  asparagus  in  any  year 
depends  upon  the  growth  made  the  previous  season,  if  this  growth  is 
measured,  we  can  get  a  general  idea  of  what  our  asparagus  will  do." 
The  conclusion  is  drawn  that  "The  results  indicate  that  culls  do  not 
make  a  good  enough  growth  to  warrant  planting,  but  the  difference 
between  first  and  seconds  was  not  enough  to  be  worth  considering." 

Those  crowns  should  be  selected  for  planting  purposes  that  are 
large  in  size,  have  large  buds,  are  fresh,  uninjured,  and  free  from 
disease. 

Crown  Desiccation. — Some  tests  were  started  at  the  University 
Farm,  Davis,  California,  in  1924  to  determine  to  what  extent  growth 
was  retarded  and  yields  reduced  when  the  crowns  were  dried  for  a 
period. 

Crowns  were  stored  in  burlap  sacks  in  a  dry  room  subject  to  the 
same  temperature  fluctuations  as  the  outside  atmosphere.  There  were 
118  crowns  in  each  sack,  a  number  sufficient  to  plant  one  row  in 
the  experimental  plot.  The  crowns  were  set  in  the  permanent  bed 
March  29,  1924,  after  being  exposed  to  atmospheric  conditions  for  a 
period  of  53  days.  The  crowns  lost  approximately  20  per  cent  of 
their  weight  during  the  time  they  were  kept  in  storage.  They  were 
planted  in  furrows  8  inches  deep  and  covered  with  about  2  inches 
of  soil.  Water  was  then  run  in  the  furrows  over  the  crowns.  At 
intervals,  a  count  was  made  of  the  crowns  having  aerial  shoots.  Even 
under  the  most  ideal  growing  conditions  it  was  34  days  before  any 
shoots  appeared  above  ground.  Fifty-two  days  after  planting  75  per 
cent  of  the  plants  had  shoots  above  ground.  Eventually  a  perfect 
stand  was  obtained. 

The  influence  of  root  desiccation  upon  the  yields  of  asparagus 
spears  during  the  first  two  cutting  seasons  is  shown  in  table  4. 

Allowing  the  crowns  to  dry  out  before  planting  caused  a  reduction 
in  yield  of  324  pounds  per  acre  the  first  year  and  426  pounds  the 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


51 


second  year  below  that  of  crowns  planted  in  the  permanent  field 
shortly  after  removing  from  the  nursery. 

Crown  Selection  and  Replanting. — Crown  selection  is  justified 
even  if  for  no  other  reason  than  to  reduce  the  amount  of  replanting. 
On  a  California  ranch,  1,814  acres  of  asparagus  were  planted  in  the 
spring  of  1921 ;  3,418  ungraded  crowns  were  set  on  each  acre.  Care 
was  taken  to  plant  the  crowns  properly  and  they  were  given  the 
required  attention  subsequently.  The  per  cent  stand  in  August, 
1922,  was  64.  This  necessitated  considerable  expense  in  replanting. 
The  labor  cost  alone  of  replanting  in  this  case  amounted  to  $1.25  per 
1,000  crowns,  and  the  crowns  needed  for  replanting  cost  $4.00  per 


TABLE  4 
Influence  of  Root  Desiccation  upon  Yield  of  Speaks 


Treatment 

Total 

number  of 

crowns 

Average 
number  of 

spears 
per  crown 

Average 
weight  of 

spears 
per  crown 

Average 

weight  of 

single 

spear 

Yield 
per  acre 
(pounds) 

1925: 
Roots  desiccated 

352 
353 

352 
353 

1.86 
5.27 

11.13 

14.89 

39.41 
90.11 

294.23 
360.31 

21.14 
17.08 

26.45 
24.20 

250.25 

Roots  not  desiccated 

1926: 
Roots  desiccated 

573.83 
1,868.38 

Roots  not  desiccated 

2,294.47 

1,000.  To  the  above  costs  of  replanting  must  be  added  the  losses  due 
to  decreased  yields.  In  the  case  cited,  38  per  cent  of  the  plants  were 
at  least  a  year  behind  the  others.  It  should  be  added  that  subsequent 
plantings  on  this  same  ranch,  on  a  similar  type  of  soil,  using,  however, 
only  selected  crowns,  resulted  in  almost  100  per  cent  stands. 

Division  of  Crowns. — Asparagus  can  be  propagated  by  division  of 
the  crown.  This  method  of  propagation,  however,  is  not  employed 
commercially.  It  was  formerly  used  to  only  a  limited  extent  in  plant- 
ing the  home  garden,  but  the  prevailing  practice  now  is  to  use  one- 
year-old  crowns.  Propagation  of  asparagus  by  division  of  the  crowns 
has  been  employed  in  breeding  operations.  If  one  wishes  to  multiply 
a  desirable  male  or  female  plant  for  breeding  purposes,  this  can  be 
done  by  division  of  the  crown.  These  can  then  be  planted  in  an 
isolated  bed. 

Root  Pruning. — Root  pruning  is  not  generally  practiced  in  plant- 
ing large  acreages  of  asparagus.  In  some  cases,  however,  growers 
prune  back  the  fleshy  roots  to  within  3  or  4  inches  of  the  buds.  This 
is  done  mainly  to  facilitate  handling  and  planting. 


52 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


The  influence  of  root  pruning  on  the  yield  of  spears  during  the 
first  two  cutting  seasons  is  shown  in  table  5.  All  plots  were  planted 
in  triplicate.  All  but  4  inches  of  the  roots  were  pruned  off,  causing 
a  loss  in  weight  of  about  25  per  cent. 

TABLE  5 
Effect  of  Root  Pruning  on  Yield  of  Spears 


Treatment 

Number 
of  crowns 

Average 
number  of 

spears 
per  crown 

Average 
weight  of 

spears 
per  crown 

Average 

weight  of 

single 

spear 

Yield 
per  acre 
(pounds) 

1925: 

Roots  pruned 

352 
353 

352 
353 

2.46 

5.27 

14.15 
14.89 

47.52 
90.11 

327.88 
360.31 

19.31 
17.08 

23.17 
24.20 

301.77 

Roots  not  pruned 

573.83 

1926: 

Roots  pruned 

2,082.05 
2,294.47 

Roots  not  pruned 

Pruning  of  the  roots  caused  a  reduction  in  yield  of  272  pounds 
per  acre  the  first  year  and  212  pounds  the  second  year.  Plants  that 
had  their  roots  pruned  at  time  of  transplanting  are  no  doubt  given 
a  more  severe  check  at  time  of  transplanting  than  those  unpruned. 
A  portion  of  the  food  reserve  is  removed,  pruned  roots  do  not  continue 
to  elongate  and  the  surface  for  the  development  of  fibrous  roots  is 
also  reduced. 


ESTABLISHING   THE   PLANTATION 

Soil  Type. — Soil  type  is  a  very  important  consideration  in  the 
profitable  production  of  asparagus.  At  present  this  crop  is  grown 
on  many  different  soil  types,  from  clay  to  sandy  loam  and  muck. 
Where  early  growth  is  necessary  for  profitable  production,  as  in  the 
Imperial  Valley  of  California,  Georgia,  South  Carolina,  New  Jersey, 
and  to  a  certain  extent,  in  the  Delta  region  of  California,  a  soil  that 
warms  rapidly  in  early  spring  has  a  decided  advantage. 

On  the  eastern  seaboard  of  the  United  States,  in  the  Middle  West, 
and  in  the  Imperial  Valley  and  San  Fernando  Valley  of  California, 
most  of  the  large  plantings  are  on  soils  varying  from  silt  to  light  sand 
and  sandy  loam.  On  sandy  soils  tillage  is  less  difficult  and  less  expen- 
sive ;  such  soils  are  well  aerated,  dry  quickly  after  a  rain  or  irrigation, 
do  not  form  a  hard  crust  over  the  row,  and  produce  a  more  uniform 
and  attractive  product  than  can  be  obtained  on  the  heavier  soil  types. 
Very  light  sandy  soils,  however,  are  not  as  desirable,  especially  if  the 
subsoil  is  a  light  sand  or  gravel.     The  subsoil  should  be  retentive  of 


BUL.  446]  THE    ASPARAGUS    INDUSTRY    IN    CALIFORNIA  53 

moisture,  and  open  and  porous  enough  to  facilitate  drainage  and  to 
allow  root  penetration  and  aeration. 

Clay  soils  are  not  desirable  for  commercial  asparagus  production, 
mainly  because  they  warm  up  too  slowly  in  the  spring.  Clay  soils  are 
also  difficult  to  manage.  While  the  yield  may  be  as  high  or  higher 
as  on  the  lighter  soils,  if  grown  for  market  the  bulk  of  the  crop  is 
produced  late  in  the  season  when  the  prices  are  low.  The  percentage 
of  crooked  spears  is  higher  on  the  heavy  than  on  the  light  soils. 

In  the  Delta  region  of  California,  practically  all  of  the  asparagus 
is  planted  on  muck  or  a  mixture  of  muck  and  river  sediment.  Muck 
makes  an  ideal  asparagus  soil ;  it  warms  up  rapidly  in  the  spring  of 
the  year;  it  is  loose  and  friable  and  the  spears  can  make  a  straight 
upward  growth.  Muck  has  a  high  water-holding  capacity  and  is 
comparatively  easy  to  work. 

Because  of  the  high  sodium  chloride  tolerance  of  asparagus  it  is 
possible  to  use  land  for  this  crop  that  has  a  salt  content  too  high  for 
the  production  of  many  other  crops.  In  the  Suisun  Bay  region  of 
California,  there  is  a  large  tract  of  land  subject  to  salt  water  irri- 
gation during  the  latter  part  of  each  summer  and  fall.  Much  salt  is 
washed  out  each  winter  during  the  rainy  season,  but  by  evaporation 
from  the  surface,  the  salt  content  increases  in  the  upper  layers 
throughout  the  summer.  The  salinity  of  these  soils  is  especially  high 
after  a  winter  of  low  rainfall,  as  the  salt  is  not  washed  out  of  the 
soils,  and,  too,  there  is  not  sufficient  fresh  water  produced  by  the 
melting  snows  of  the  high  Sierras  to  keep  the  highy  concentrated 
saline  waters  flushed  out  of  the  lower  river  channels.  Asparagus 
planted  on  these  saline  soils  has  done  exceptionally  well.  It  is  the 
practice  in  the  Delta  to  stop  using  the  river  water  for  irrigation 
purposes  when  the  sodium  chloride  content  reaches  1  part  in  1,000. 
The  margin  of  safety  here  is  very  large,  for  asparagus  will  withstand 
a  higher  concentration  than  this. 

Previous  Crop. — There  is  little  known  concerning  the  influence  of 
the  previous  crop  upon  the  growth  of  asparagus.  Previous  crops 
should  be  such  as  to  leave  the  soil  loose,  friable,  capable  of  being  easily 
worked  and  free  from  weeds. 

The  Lay  of  the  Land. — Where  surface  irrigation  is  necessary, 
there  should  be  about  2  or  3  inches  of  fall  to  every  100  feet  of  row. 
Where  subirrigation  is  practiced,  the  beds  should  be  as  nearly  level 
as  possible  so  that  the  plants  will  receive  water  uniformly  throughout 
the  field.  If  the  land  is  uneven,  the  high  spots  will  not  receive 
sufficient  water  and  the  low  areas  will  be  difficult  to  drain. 


54  UNIVERSITY   OF    CALIFORNIA EXPERIMENT    STATION 

Direction  of  Rows. — If  possible  the  rows  of  asparagus  should  run 
parallel  with  the  prevailing  winds.  This  gives  good  aeration,  dries 
the  plants  early  in  the  morning,  in  case  dews  are  prevalent,  and  also 
prevents  the  stalks  from  being  broken  down  across  the  middles  after 
the  cutting  season,  thus  interfering  with  cultivation.  In  the  Delta, 
it  is  especially  desirable  that  the  rows  run  parallel  with  the  prevailing 
wind  as  the  soil  is  very  light;  strong  winds  blowing  at  right  angles 
to  the  ridge  remove  dirt  from  the  ridges,  continually  lowering  them 
during  the  cutting  season.  When  surface  irrigation  is  practiced,  it 
is,  of  course,  necessary  to  run  the  rows  with  the  slope  of  the  land  in 
order  to  facilitate  the  flow  of  water. 

Time  of  Planting. — In  most  sections  of  the  country,  asparagus 
crowns  are  set  as  early  in  the  spring  as  the  ground  can  be  worked. 
In  the  Delta,  planting  is  usually  done  at  almost  any  time  during  the 
winter  when  conditions  are  favorable.  Late  fall  or  early  winter 
planting  is  advisable  because  in  years  of  normal  rainfall  it  is  difficult 
to  do  any  planting  until  after  the  heavy  rains  have  stopped.  In  the 
Imperial  Valley  of  California,  the  fields  can  be  planted  any  time 
during  the  winter,  as  the  rains  do  not  interfere. 

It  is  best  to  set  the  crowns  before  the  buds  have  started  into 
growth  and  as  soon  as  possible  after  digging  from  the  nursery. 

Distance  between  Rows. — The  distance  between  rows  of  asparagus 
will  depend  upon  a  number  of  factors :  the  nature  of  the  product  to 
be  harvested,  the  fertility  of  the  soil,  and  the  cultural  methods  to  be 
employed.  In  growing  white  asparagus,  it  is  necessary  to  hill  or  ridge 
the  crowns.  In  this  case,  the  height  of  the  ridge  employed  determines 
to  a  certain  extent  the  distance  between  rows,  for  there  must  be 
sufficient  soil  volume  between  them  to  form  the  ridges,  In  California, 
where  white  asparagus  is  commonly  grown,  the  usual  distance  between 
rows  is  ly^  to  8  feet.  Green  asparagus  is  usually  given  a  very  low 
ridge  or  is  not  ridged  at  all;  consequently,  the  rows  may  be  closer 
together,  the  usual  distance  being  6  to  8  feet.  Many  of  the  eastern 
growers  who  produce  green  asparagus  plant  the  rows  as  close  as  4% 
feet.  In  comparison  with  wide  spacing,  a  crowded  asparagus  bed 
produces  an  inferior  product,  both  in  size  and  quality;  furthermore, 
the  productive  life  of  the  bed  is  shorter.  French  asparagus  growers 
plant  more  closely  than  American  growers;  but  the  French  growers 
fertilize  their  crop  more  heavily  and  rely  upon  hand  labor  almost 
entirely. 

Spacing  in  the  Row. — There  is  much  variation  in  the  spacing  of 
plants  in  the  rows.  The  distance  between  the  rows  must  be  taken 
into  consideration.     The  root  system  of  an  asparagus  plant  is  exten- 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


55 


sive,  and  even  with  an  8-foot  spacing  between  rows,  in  a  few  years 
the  roots  of  adjacent  rows  interlace.  In  the  large  plantings  of  Cali- 
fornia, the  usual  spacing  between  plants  in  the  row  is  18  to  20  inches ; 
this  is  with  a  distance  of  7%  to  8  feet  between  rows.  The  present 
tendency  in  the  asparagus  regions  of  California  is  to  place  the  plants 
farther  apart  in  the  row  than  has  been  the  practice  heretofore.  Many 
growers  are  now  setting  crowns  24  inches  apart.  Closely  planted  beds 
yield  the  largest  crops  while  the  bed  is  young,  but  the  spears  are  not 
so  large  after  the  first  two  or  three  years  as  where  the  plants  are 
spaced  farther  apart.  Table  6  has  been  compiled  as  a  guide  to  the 
number  of  crowns  required  to  plant  an  acre. 


TABLE  6 

Number  of  Crowns  Eequired  to  Plant  an  Acre  for  Different 

Spacing  Distances 


Distance  between 

Distance  between  rows,  (feet) 

plants  in  the  row, 
(inches) 

4 

5 

6 

7 

7.5 

8 

9 

12 

10,890 

8,712 

7,260 

6,223 

5,808 

5,445 

4,840 

15 

8,712 

6,969 

5,808 

4,978 

4,620 

4,356 

3,872 

18 

7,260 

5,808 

4,840 

4,148 

3,872 

3,630 

3,226 

24 

5,445 

4,356 

3,630 

3,111 

2,904 

2,722 

2,420 

30 

4,356 

3,485 

2,904 

2,489 

2,310 

2,178 

1,936 

36 

3,630 

2,904 

2,420 

2,074 

1,936 

1,815 

1,613 

42 

3,111 

2,489 

2,074 

1,775 

1,659 

1,534 

1,382 

Methods  of  Trenching. — In  the  large  asparagus  plantations  of 
California,  the  trenches  are  usually  dug  by  use  of  a  middle-breaker 
with  wings  or  extensions  attached  to  the  moldboards,  and  pulled  by 
tractor  power  (fig.  23).  One  or  two  trenches  are  made  at  a  time.  The 
depth  varies  from  8  to  12  inches,  depending  upon  the  type  of  soil. 

Depth  of  Planting. — As  just  stated,  the  type  of  soil  is  a  factor  in 
determining  the  depth  of  planting;  in  a  light  soil,  the  crowns  can  be 
set  deeper  than  in  a  heavy  soil.  In  the  light  peat  soils  of  the  Delta, 
the  usual  depth  of  planting  is  10  to  12  inches.  Many  years  ago  it 
was  customary  to  plant  asparagus  crowns  very  deep,  often  as  much 
as  18  inches.  This  practice  is  usually  unsatisfactory  because  the 
growth  starts  more  slowly  in  the  spring,  which  makes  the  crop  late. 

The  data  given  in  table  7,  from  experiments  conducted  at  Univer- 
sity Farm,  Davis,  give  the  influence  of  depth  of  planting  upon  spear 
production  the  first  two  cutting  seasons.  The  soil  type  is  a  silt  loam. 
All  plots  were  planted  in  triplicate. 


56 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 


Deep  planting  (12  inches)  caused  a  reduction  in  yield  the  first 
year  of  377  pounds  per  acre  and  727  pounds  the  second  year  when 
compared  with  crowns  planted  more  shallow  (8  inches).  It  is  entirely 
possible  that  the  deeply  planted  plants  would  have  given  a  better 
account  of  themselves  had  the  length  of  the  cutting  season  been 
extended. 


mmgamm**^ 


Fig.  23. — One  method  of  furrowing,  preparatory  to  planting  croAvns. 
The  furrows  are  8  to  12  inches  deep. 

TABLE  7 
Influence  of  Depth  of  Planting  on  Yield  of  Spears 


Depth  of 
planting 
(inches) 

Number 
of  crowns 

Average 
number  of 

spears 
per  crown 

Average 
weight  of 

spears 
per  crown 

Average 

weight  of 

single  spear 

(grams) 

Yield  of  spears 
per  acre 
(pounds) 

1925: 

8 

353 

5.27 

90.11 

17.08 

573.83 

12 

346 

1.36 

31.54 

23.12 

196.88 

1926: 

8 

353 

14.89 

360.31 

24.20 

2,294.47 

12 

346 

9.21 

251.09 

27.25 

1,567.26 

Placing  Crowns. — The  crowns  may  be  hauled  to  the  fields  loose  on 
large  racks  (fig.  24)  or  in  burlap  sacks.  If  the  rows  are  short,  the 
crowns  are  placed  in  piles  at  the  end  of  the  furrows.  If  the  rows  are 
long,  they  are  placed  in  piles  throughout  the  field.  The  droppers 
usually  carry  the  crowns  in  burlap  sacks  swung  from  their  shoulders 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


57 


(fig.  25).  The  distance  between  crowns  is  merely  estimated.  Pains 
are  taken  to  drop  the  crowns  so  that  the  buds  are  up.  As  a  rule,  in 
the  large  plantings  no  attempt  is  made  to  spread  the  fleshy  roots 
uniformly. 


Fig.  24. — Hauling  asparagus  crowns  to  the  field. 


Fig.  25. — Dropping  the  crowns  in  the  trenches.     The  man  in  the 
foreground  carries  a  sack  which  holds  the  crowns. 


58 


UNIVERSITY   OP    CALIFORNIA — EXPERIMENT   STATION 


Covering  the  Crowns. — This  operation  should  be  done  if  possible 
the  same  day  the  crowns  are  planted.  The  type  of  soil  will  determine 
to  some  extent,  the  depth  to  cover  the  crowns  immediately  after 
planting.  The  best  practice  is  to  cover  with  about  2  or  3  inches  of  soil. 
If  the  full  depth  of  soil  is  placed  on  the  crowns  immediately  after 
they  are  planted,  there  is  danger  of  smothering  the  new  growth. 

The  method  of  covering  the  crowns  varies  somewhat.  A  common 
and  also  an  excellent  practice  is  to  cover  them  by  hand  with  a  hoe. 
Almost  any  type  of  horse  implement  can  be  used  that  moves  a  small 
amount  of  soil  free  from  clods  into  the  trenches. 


Fig.  26. — Asparagus  bed,  intercropped  with  beans. 
Crowns  set  in  field  1923;  photo  taken  July  25,  1924. 

As  soon  as  the  young  plants  begin  to  send  sprouts  through  the 
soil  covering,  more  soil  is  moved  into  the  furrow;  this  operation  is 
repeated  at  intervals  throughout  the  season,  so  that  by  midsummer 
the  fields  are  usually  being  given  level  cultivation. 

Cultivation  of  the  Plantation  the  First  Year. — Filling  in  the 
furrows  and  cultivating  between  the  rows  is  about  all  the  tillage  the 
bed  needs  the  first  year.  The  few  weeds  that  appear  in  the  row  are 
easily  smothered  by  moving  soil  into  the  furrow  from  time  to  time. 

Handling  the  Plantation  during  the  First  Fall  and  Winter. — It  is 
best  not  to  cut  the  top  growth  until  it  has  been  killed  by  frost.  It  is 
then  no  longer  active  in  the  manufacture  of  carbohydrates,  and  the 
movement  of  food  to  the  roots  has  ceased.  There  is  no  longer  any 
advantage  in  retaining  the  top  growth  unless,  as  practiced  in  some 
sections,  it  is  left  to  act  as  a  cover  crop  throughout  the  winter. 


BUL.  446]  THE   ASPARAGUS   INDUSTRY    IN    CALIFORNIA  59 

Replanting. — The  time  to  locate  the  missing  plants  is  in  late  fall, 
before  the  tops  are  cut.  The  field  should  be  gone  over  carefully,  and 
holes  dug  where  crowns  are  missing.  The  replanting  may  be  done 
any  time  during  late  fall,  winter,  or  early  spring. 

Intercropping. — It  is  a  very  common  practice  to  intercrop  the 
asparagus  beds  the  first  year.  For  this  purpose  beans  are  usually 
employed.  Other  crops  sometimes  used  are  potatoes,  carrots,  peas, 
peppers,  early  cabbage,  radishes,  and  lettuce.  Asparagus  should  not 
be  intercropped  with  plants  that  grow  tall  and  produce  a  large  amount 
or  shade  or  that  twine  about  the  asparagus  tops  and  smother  them. 

A  number  of  successful  growers  regard  intercropping  as  inadvis- 
able. They  believe  that  intercrops  do  not  permit  clean  cultivation 
close  to  the  asparagus  plants  and  that  they  use  soil  nutrients  needed 
by  the  asparagus.  In  many  cases  intercropping  the  first  year  is  an 
economic  necessity,  tiding  the  grower  over  until  the  asparagus  fields 
come  into  bearing. 


MANAGEMENT  OF  THE  ASPARAGUS  PLANTATION  THE  SECOND 
AND  SUBSEQUENT  YEARS 

The  methods  of  handling  the  asparagus  plantation  after  the  first 
year  vary  in  the  different  countries  and  districts  and  even  on  adjoin- 
ing farms  in  the  same  district.  While  management  can  be  discussed 
only  in  a  general  way,  there  are  usually  certain  major  operations 
practiced  alike  by  almost  all  the  growers  in  the  same  locality.  Often 
certain  practices  are  followed  mainly  because  of  established  precedent, 
but  more  often  these  have  been  evolved  to  meet  the  cultural  require- 
ments of  the  region. 

In  France. — The  asparagus  fields  in  the  Argenteuil  district  of 
France  are  not  cut  until  the  spring  of  the  third  year,  and  even  then 
the  cutting  is  light.  Each  fall,  usually  in  October,  the  mature  stalks 
are  cut,  the  soil  removed  from  the  mounds,  leaving  but  a  few  inches 
of  soil  covering  the  crowns.  Eacji  spring,  usually  in  March,  the  soil  is 
hilled  over  the  crowns  again.  The  third,  fourth  and  fifth  years  the 
mounds  are  made  approximately  7,  9,  and  11  inches  high,  respectively. 
They  are  made  higher  and  wider  as  the  beds  become  older.  It  will  be 
recalled  that  the  asparagus  crown  tends  to  grow  upward,  and  to  spread 
laterally  as  it  ages.  Only  two  or  three  spears  are  cut  from  each  crown 
the  third  year.  The  fourth  year,  however,  harvesting  may  continue  for 
three  weeks.  The  fifth  year  cutting  may  last  from  four  to  six  weeks. 
After  this  the  fields  are  usually  cut  the  entire  season  of  seven  to  eight 


60  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

weeks.  Harvesting  usually  starts  in  early  April  and  ends  the  fore 
part  of  June.  On  light  soils  the  profitable  life  of  a  bed  is  about  ten 
years;  on  heavy  and  rich  soil  it  may  be  more  than  twenty  years.  It 
is  the  experience  in  France  that  after  an  asparagus  bed  is  plowed  up 
the  land  should  not  be  replanted  to  this  crop  for  twenty-five  or  thirty 
years. 

In  the  Eastern  and  Middle  Western  States. — In  the  eastern  and 
middle  western  states,  harvesting  is  seldom  done  until  the  third  year. 
In  South  Carolina  and  contiguous  states,  however,  which  have  a  longer 
growing  season  than  the  states  northward,  some  fields  are  cut  the 
second  year.  Those  beds  not  cut  the  second  year  are  handled  as 
during  the  first.  Some  growers  burn  the  dry  stalks  in  late  fall,  but 
in  many  districts  the  stalks  are  left  standing  over  the  winter  to  hold 
the  snow  and  prevent  the  blowing  of  the  soil.  Burning  the  stalks  is 
not  to  be  recommended  especially  on  mineral  soils  that  are  low  in 
organic  matter.  In  early  spring  when  the  soil  is  sufficiently  dry,  the 
stalks  are  disked  or  plowed  under.  The  method  of  disposing  of  the 
stalks  is  usually  the  same  throughout  the  life  of  the  bed.  The  third 
year  the  fields  are  cut  for  a  period  of  two  to  four  weeks,  depending 
upon  the  vigor  of  the  crowns.  In  the  green  " grass"  districts,  level 
cultivation  is  usually  given.  In  some  parts  of  Maryland,  Delaware, 
and  New  Jersey,  where  asparagus  is  still  blanched  for  the  market, 
the  ridges  are  made  by  the  use  of  cultivators,  disks,  or  plows,  and 
other  specially  constructed  implements.  As  these  ridges  are  lowered 
during  the  harvesting  season  by  the  rain  and  the  cutting  operations, 
they  are  rebuilt  from  time  to  time.  At  the  close  of  the  cutting  season 
the  ridges  are  disked  or  plowed  down  and  level  cultivation  is  given 
during  the  remainder  of  the  season.  During  the  fourth  and  subsequent 
years,  the  beds  are  handled  in  much  the  same  way  as  during  the  third 
year,  except  that  the  cutting  season  is  more  extended. 

In  Imperial  Valley,  California, — In  the  Imperial  Valley,  some 
harvesting  can  be  done  the  second  year,  if  the  plants  have  made  a 
good  growth  the  previous  season.  The  third  and  subsequent  years 
the  beds  are  usually  cut  the  entire  season.  It  is  the  custom  to  disk 
the  stalks  into  the  soil  during  December  or  early  January. 

Almost  all  of  the  asparagus  in  the  Imperial  Valley  is  grown  for 
the  early  market,  and  if  the  ridges  are  high,  the  soil  about  the  crown 
buds  warms  up  slowly,  early  growth  is  delayed,  and  it  takes  longer 
for  the  spear  to  grow  through  the  deep  covering  of  soil  and  attain 
marketable  length.  There  is  also  danger  of  the  heads  opening 
before  the  desired  length  of  green  is  obtained.     The  usual  height  of 


BUL.  446]  THE   ASPARAGUS   INDUSTRY   IN    CALIFORNIA  61 

the  ridge  is  3  or  4  inches.  The  ridges  over  the  rows,  however,  should 
be  made  sufficiently  high  to  prevent  flooding  at  time  of  irrigation. 
Water  is  applied  early  in  January.  If  the  soil  is  warm,  this  early 
irrigation  forces  the  buds  into  growth.  Frequent  irrigations  are  given 
during  the  cutting  season.  At  any  one  irrigation,  water  is  applied  to 
alternate  furrows,  the  unirrigated  middles  being  used  as  walks  for 
the  cutters.  At  the  following  application,  water  is  turned  into  the 
furrows  not  irrigated  the  preceding  time.  Frequent  irrigation  is 
necessary  in  the  Imperial  Valley,  as  the  evaporation  rate  is  very  high 
and  there  is  almost  no  rainfall  throughout  the  year.  Cutting  usually 
starts  early  in  February  and  continues  until  shipping  is  no  longer 
profitable.  This  is  usually  about  April  15  but  may  be  as  late  as  May  1. 
At  the  close  of  the  cutting  season,  the  ridges  are  disked  down  to 
destroy  weeds  and  loosen  the  soil,  but  are  again  rebuilt  to  facilitate 
irrigation  and  to  prevent  flooding  and  the  formation  of  a  crust  over 
the  row.  It  is  desirable  to  secure  a  good  growth  of  tops  as  soon  as 
possible  after  the  cutting  season.  This  growth  is  usually  obtained  by 
applying  a  top  dressing  of  75  to  100  pounds  per  acre  of  nitrate  of 
soda  or  sulfate  of  ammonia  and  then  irrigating.  The  extremely  hot 
weather  during  July  and  August  checks  new  growth,  but  water  should 
be  applied  in  order  to  keep  the  stalks  green  so  that  the  manufacture 
of  food  may  continue.  Cultivation  is  necessary  after  each  irrigation. 
After  late  August  or  early  September,  irrigation  is  discontinued  in 
order  that  additional  buds  may  not  be  forced  into  growth  during  the 
fall  and  thus  use  the  food  reserves  stored  in  the  roots. 

A  few  growers  in  the  Imperial  Valley  are  now  cutting  asparagus 
in  the  fall  of  the  year.  The  fields  are  matured  early  by  withholding 
water.  Then  the  stalks  are  cut,  dried,  and  burned,  or  disked  into  the 
soil  and  water  applied  to  start  the  buds  into  growth.  The  plants  have 
an  exceptionally  long  period  for  growth  and  food  storage  in  the 
Imperial  Valley.  For  this  reason,  it  may  be  possible  to  develop 
methods  of  handling  so  that  the  same  beds  may  be  cut  for  a  short  time 
in  both  the  spring  and  fall  of  the  year  when  the  returns  are  most 
favorable.  However,  there  are  indications  that  spring  cutting  is 
delayed  on  beds  that  have  been  cut  in  the  fall. 

In  Delta  Region,  California. — The  methods  of  handling  asparagus 
plantations  in  the  California  Delta  are  many,  and  some  of  them 
unique.  It  is  the  general  practice  to  cut  the  fields  the  second  year 
throughout  a  part  or  all  of  the  green  "grass"  season,  unless  for  some 
reason  there  was  only  a  poor  growth  the  previous  year.  During  the 
third  year  cutting  may  continue  until  July  if  the  beds  do  not  show 


62 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


signs  of  exhaustion.  In  the  late  fall  after  the  tops  have  been  killed 
by  frost,  they  are  cut  with  a  mowing  machine,  and  when  sufficiently 
dry  are  burned.  On  the  light  peat  and  muck  soils  the  tops  cannot  be 
burned  until  after  the  surface  soil  has  been  well  wetted  from  rain 
as  there  is  danger  of  the  soil  burning  also.  A  low  ridge  of  soil  is 
then  thrown  over  the  row  by  use  of  a  disk  to  cover  the  stubble  and 
facilitate  its  decomposition  during  the  winter. 

In  the  late  fall  or  winter,  the  soil  between  the  rows  is  sometimes 
subsoiled  to  a  depth  of  12  to  15  inches.  This  aerates  the  soil,  facilitates 


Fig.  27. — Eidging  asparagus  with  a  disk. 


the  percolation  of  water  through  it,  and  causes  it  to  warm  up  quickly 
the  following  spring.  Although  the  subsoilers  are  run  midway 
between  the  two  rows,  some  of  the  fleshy  roots  are  destroyed.  It  is 
not  known  definitely  whether  the  advantages  accruing  from  subsoiling 
more  than  compensate  for  this  injury  to  the  roots. 

The  first  operation  in  preparation  for  the  cutting  season  is  usually 
the  disking  of  the  soil  from  the  rows.  This  cuts  off  the  bases  of  the 
stalks  and  loosens  the  soil  over  the  crown.  A  low  ridge  is  then  thrown 
back  over  the  row.  The  ridges  for  green  asparagus  are  made  from 
4  to  6  inches  high.  Usually  two  disking  operations  are  required. 
A  chain  is  sometimes  dragged  after  the  disk  to  break  the  clods  and 
smooth  the  ridge.  A  harrow  or  flexible  board  float  made  to  conform 
to  the  shape  of  the  ridge  is  sometimes  pulled  behind  the  disk  (fig.  28). 
After  disking,  a  ridge  harrow  is  often  used  alone  or  in  combination 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


63 


with  a  wooden  float.  In  the  older  beds,  a  higher  and  wider  ridge  is 
required  than  in  the  younger  ones.  During  the  green  "grass"  season, 
cultivation  is  mainly  between  the  rows. 

Preparatory  to  cutting  white  asparagus  for  canning,  the  low  ridges 
are  usually  disked  down.  Though  a  large  number  of  young  spears  are 
destroyed,  it  is  probably  the  only  profitable  method  that  can  be 
employed  to  kill  the  weeds  and  loosen  the  soil.  The  ridges  are 
immediately  rebuilt  and  are  made  much  higher  than  when  green 
asparagus  is  cut.  Each  ridge  is  made  15  to  20  inches  high,  depending 
upon  the  age  of  the  bed.     The  ridges  are  made  higher  each  year  in 


Fig.  28. — A  board  float  is  often  attached  behind  the  disks. 


order  to  get  the  desired  length  of  spear,  and  to  prevent  injury  to  the 
crown  in  cutting.  They  must  also  be  made  wider  each  year,  as  the 
spread  of  the  crown  increases.  During  the  cutting  season  for  the 
cannery,  the  beds  must  be  rebuilt  every  few  weeks.  At  the  end  of 
the  cutting  season  they  are  disked  down  and  the  fields  are  given  level 
cultivation  the  remainder  of  the  growing  season.  The  middles  between 
the  rows  are  worked  constantly  during  and  after  the  cutting  season 
with  disks,  cultivators,  drags,  and  floats.  When  the  "fern"  appears, 
hand  hoeing,  as  well  as  cultivation,  is  employed.  On  some  farms 
horses  are  used  almost  entirely,  while  on  others  tractors  are  used 
whenever  possible. 

It  is  on  the  reclaimed  lands  of  the  Delta  that  most  of  the  asparagus 
in  California  is  grown.  Not  many  years  ago  the  overflow  delta  lands 
were  growing  little   else  than  the   marsh   "tule"    (mainly,   Scirpus 


64  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

lacustris  var.  occidentalis) .  The  growth  of  vegetation  and  the  decom- 
position and  accumulation  of  organic  matter  throughout  the  centuries 
have  built  up  one  of  the  most  productive  and  fertile  soils  that  can  be 
found  anywhere  in  the  world.  Formerly,  nearly  all  of  the  Delta 
land  was  subject  to  inundation.  Enterprising  capital,  however,  has 
built  large  levees  and  confined  the  one-time  meandering  streams  and 
flood  waters  to  well  defined  channels ;  at  present  almost  all  of  the  land 
is  protected  from  overflow.  Generally,  the  level  of  the  asparagus  land 
is  below  that  of  the  water  in  the  streams,  and  irrigation  is  carried  on 
by  siphoning  and  pumping  the  water  from  the  rivers  and  network  of 
waterways  that  surround  the  islands  into  large  ditches  that  carry  it  to  a 
system  of  laterals  throughout  the  fields.  The  soil  is  open  and  porous, 
and  when  the  water  is  raised  in  the  ditches  the  water  table  is  elevated 
throughout  the  entire  soil  area.  The  water  is  raised  to  within  a  few 
inches  of  the  surface  and  is  then  pumped  back  into  the  river  until 
the  water  level  of  the  land  reaches  the  desired  depth,  which  is  usually 
from  4  to  6  feet.  The  time  of  irrigation  and  the  number  of  irrigations 
given  vary  with  conditions.  If  rainfall  during  the  winter  has  been 
light,  then  irrigation  will  necessarily  start  earlier  in  the  spring  than 
if  the  soil  had  been  well  wetted  by  a  heavy  rainfall.  It  is  occasionally 
necessary  to  stop  irrigation  early  in  the  summer  especially  after 
seasons  of  drought  similar  to  the  one  experienced  during  the  winter 
of  1923-24;  for  when  there  is  not  sufficient  fresh  water  supplied  by 
the  melting  snow  in  the  Sierra  Nevadas,  the  brackish  water  from 
Suisun  Bay  moves  up  the  streams  for  a  considerable  distance. 

In  the  lower  Delta  near  Suisun  Bay,  there  is  a  difference  of  several 
feet  between  high  and  low  tide.  This  makes  it  possible  to  irrigate  at 
high  tide  and  drain  the  land  at  low  tide.  At  high  tide  the  flcod  gates 
are  opened  and  the  water  is  run  into  large  irrigation  ditches.  When 
sufficient  water  has  been  added,  the  gates  are  closed.  When  irrigation 
is  complete,  at  low  tide  the  gates  on  the  levees  are  again  opened  and 
the  water  drained  off.  It  takes  some  time  to  lower  the  water  table 
in  the  soil  after  irrigation.  The  minus  tides  are  not  always  sufficiently 
low  to  give  the  desired  depth  of  water  table,  so  some  water  is  pumped 
back  into  the  stream.  In  this  region,  in  seasons  of  normal  rainfall, 
irrigation  must  stop  some  time  in  July  because  of  the  high  salt  content 
of  the  water;  in  seasons  of  low  rainfall,  irrigation  usually  stops 
somewhat  earlier. 


BUL.  446]  THE    ASPARAGUS    INDUSTRY    IN    CALIFORNIA  65 


FACTORS  INFLUENCING  THE  YIELD  OF  ASPARAGUS 

The  yield  of  asparagus  from  a  plantation,  considered  for  any  one 
year  or  for  a  series  of  years,  is  influenced  by  a  number  of  factors, 
chief  of  which  are :  age  of  crown,  temperature,  fertility  of  the  soil, 
cultural  methods,  moisture,  variety,  fungous  diseases  and  insect 
enemies,  size  of  crown  at  the  time  of  planting,  and  sex  of  plants.  All 
except  the  first  two — age  of  crown  and  temperature — are  discussed 
elsewhere  in  this  bulletin. 

Age  of  Crown. — The  yield  of  an  asparagus  bed  gradually  increases 
until  the  seventh  or  eighth  year,  after  which  there  is  usually  a  gradual 
decline.  The  average  production  per  acre  in  California  over  a  period 
of  eleven  years  is  given  below. 

Yield  per  acre 
Year  (pounds) 

First  (year  planted) 0 

Second 500 

Third 1,000 

Fourth 2,000 

Fifth 4,000 

Sixth 4,250 

Seventh 4,500 

Eighth 5,000 

Ninth..., 5,000 

Tenth 4,750 

Eleventh 4,500 

Total 35,000 

Loisel(14)  gives  the  annual  production  per  acre  at  Chen-Saint 
Florentin  (France)   as  follows: 

Fourth  year 2,300  pounds 

Fifth  to  twelfth  year 3,100  pounds  per  year 

Thirteenth,  fourteenth  and  fifteenth  years,  average 2,375  pounds  per  year 

At  Cherburg  (France)  he  gives  the  following  annual  production 
per  acre : 

Fourth  year 1,750  to  2,375  pounds 

Fifth  to  twelfth  year 3,170  to  3,300  pounds  per  year 

Thirteenth,  fourteenth  and  fifteenth  years,  average. ...2,640  pounds  per  year 
Total  yield  for  period 35,030  to  36,697  pounds 

The  probable  life  of  an  asparagus  bed  is  a  factor  of  considerable 
economic  importance.  When  profitable  production  from  a  large 
plantation  of  this  kind  ceases,  it  often  imposes  a  considerable  reorgan- 


66  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

ization  of  farming  operations.  Consequently,  the  addition  of  a  year 
or  two  to  the  profitable  life  of  a  bed  is  very  significant. 

Reference  to  the  literature  shows  that  the  average  life  of  a  com- 
mercial planting,  during  which  period  the  yields  are  profitable,  is 
from  10  to  16  years. 

Loisel(14)  says  that  in  light  soil  a  bed  lasts  no  longer  than  10  years, 
but  that  in  heavier  and  rich  soils  it  may  last  more  than  20  years.  He 
further  points  out  that  when  such  a  bed  is  exhausted,  asparagus 
should  not  be  set  out  in  the  same  place  for  25  to  30  years. 

In  the  Delta  region  of  California,  the  beds  in  peat  soil  are  shorter 
lived  than  those  growing  in  sediment. 

Ilott(12)  cites  a  case  of  "some  beds  in  a  grand  old  garden  of 
Devonshire  which  had  a  history  of  at  least  90  years,  and  in  Cornwall 
I  know  a  bed,  the  proprietor  of  which  is  probably  40  years  of  age, 
this  bed  having  been  planted  by  his  father  before  the  present  owner 
was  born,  and  yet  it  produces  splendid  shoots." 

The  Causes  of  Aging  of  the  Crowns. — Various  explanations  have 
been  offered  to  account  for  the' "running  out"  of  an  asparagus  bed. 
Chief  of  these  are  the  exhaustion  of  the  soils  and  the  elevation  of  the 
crowns. 

Exhaustion  of  the  Soil. — It  is  well  known  that  every  plant  takes 
from  the  soil  quantities  of  mineral  elements,  and  that  any  particular 
kind  of  plant  has  its  own  peculiar  mineral  requirements.  Reference  to 
pages  36  and  37  will  show  the  mineral  nutrients  removed  from  the  soil 
by  an  asparagus  crop.  It  will  be  observed  from  these  data  that  of  the 
three  principal  nutrient  requirements  (nitrogen,  phosphoric  acid,  and 
potash),  the  demands  are  relatively  great  for  nitrogen  and  potash. 
One  would  naturally  reason  that  if  exhaustion  of  the  essential  mineral 
compounds  from  the  soil  were  the  cause  of  the  deterioration  in  the 
asparagus  bed,  then  the  yearly  application  of  these  ingredients  in  the 
form  of  manure  or  commercial  fertilizer,  or  both,  would  maintain 
the  yield.  It  appears,  however,  that  the  proper  application  of  fer- 
tilizers increases  the  yields  on  certain  types  of  soils,  but  the  profitable 
life  of  the  bed  is  not  materially  lengthened. 

The  root  system  of  an  asparagus  plant,  even  at  the  end  of  the 
sixth  year,  is  extensive  and  forms  a  very  compact  mass.  As  shown  on 
page  17,  a  six-year-old  crown  bore  1,012  fleshy  roots  with  a  total 
estimated  length  of  3,414  feet.  Most  of  these  roots  occupied  a  soil 
volume  of  approximately  108  cubic  feet.  When  one  digs  a  root  system 
of  this  age  or  older,  he  is  impressed  with  the  fact  that  the  roots 
actually  do  occupy  a  very  large  proportion  of  the  space  in  which 


BuL.  446]  THE   ASPARAGUS   INDUSTRY   IN    CALIFORNIA  67 

they  are  growing,  and  it  is  immediately  suggested  that  a  condition 
similar  to  that  of  a  "root-bound"  potted  plant  is  being  approximated. 
Possibly,  deterioration  of  asparagus  with  age  is  in  part  due  to  this 
condition.  If  this  is  true,  one  would  expect  a  bed  with  plants  set  far 
apart  to  have  a  longer  life  duration  than  one  in  which  the  plants  are 
crowded. 

Elevation  of  the  Crown. — It  is  well  known  that  the  asparagus 
crown  grows  toward  the  ground  surface.  As  the  bed  grows  older, 
the  shoots  arise  from  higher  and  higher  levels.  It  was  formerly  the 
practice  in  some  sections  to  plant  the  crowns  as  deep  as  18  inches, 
believing  that  by  so  doing  the  life  of  the  bed  would  be  prolonged. 
The  assumption  was  that  deterioration  was  due,  at  least  in  part,  to 
crown  elevation,  and  that  deep  planting,  therefore,  would  make  pro- 
duction profitable  over  a  longer  period.  This  practice  of  extremely 
deep  planting  has  been  largely  given  up,  because  the  crop  harvested 
from  deep  planted  crowns  is  late  and  the  rate  of  elevation  the  first 
few  years  of  a  deeply  planted  crown  is  much  greater  than  of  one 
planted  shallower.  While  the  branches  of  a  crown  planted  at  the 
usual  depth  of  10  or  12  inches  grow  diagonally  toward  the  surface, 
those  of  one  planted  at  a  depth  of  18  inches  or  more  grow  almost 
vertically  for  the  first  few  years,  or  until  such  time  that  they  attain 
a  certain  level.  Consequently,  the  supposed  advantages  of  very  deep 
planting  are  overcome  after  a  few  years. 

The  larger  spears  develop  from  buds  at  the  end  of  the  rhizome. 
The  smaller  spears  usually  come  from  buds  that  have  been  dormant 
along  the  sides  of  the  main  rhizome.  As  the  branches  come  near  the 
surface,  many  of  the  terminal  buds  are  destroyed  by  cultivation,  thus 
forcing  the  lateral  buds  into  growth.  This  probably  accounts,  at  least 
in  part,  for  the  great  increase  in  the  number  of  spindly  shoots  as  the 
beds  become  older. 

It  must  be  admitted  that  there  are  no  reliable  experimental  data 
relative  to  the  factors  causing  the  "running  out"  of  the  asparagus 
plantation.  All  of  the  factors  mentioned  above  may  play  a  part.  To 
these  should  be  added  that  of  senility,  about  which  little  is  known, 
however.  Individual  plants,  as  well  as  animals,  grow  old.  They  pass 
through  a  period  of  productivity,  after  which  there  is  a  decline.  The 
decline  is  probably  due  to  inherent  internal  factors,  as  well  as  to 
external  ones. 


68  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


VARIETIES 

Early  Mention  of  Asparagus  Varieties. — In  Greek  and  Roman 
times,  it  appears  that  a  distinction  was  made  between  "wild 
asparagus ' r  and  ' '  cultivated  asparagus. ' '  The  wild  asparagus  of  the 
Greeks  was  known  as  orminos  and  myacanthos,  and  by  the  Romans 
as  corruda.  It  is  quite  probable  that  the  only  differences  between  these 
two  were  such  as  were  due  to  garden  care.  Cato  speaks  of  the 
asparagus  which  grew  spontaneously  upon  the  island  of  Nesis,  off  the 
coast  of  Campania,  as  being  the  best  of  all.  Further,  the  asparagus 
from  the  gardens  of  Ravenna  was  extolled  for  its  high  quality,  though 
Martial  says  that  it  was  no  better  than  so  much  wild  asparagus. 
These  statements  probably  indicate  that  there  was  at  that  time  no 
markedly  distinct  cultural  varieties  of  asparagus. 

Origin  of  the  Holland  and  Argenteuil  Varieties. — It  was  not 
until  the  l$th  century  that  important  progress  was  made  in  the 
improvement  of  cultivated  asparagus.  Early  in  this  century  there 
originated  the  "violet  asparagus  of  Holland,"  Purple  Holland  or 
Purple  Dutch,  a  variety  supposedly  producing  much  larger  spears 
than  had  been  grown  before.  From  this  Holland  variety,  there  were 
obtained  from  seedling  selections  the  two  well-known  Argenteuil 
varieties,  Late  Argenteuil  and  Early  Argenteuil.  The  Late  Argen- 
teuil was  originated  in  1860  by  Lherault-Solboeuf,  an  asparagus 
grower  at  Argenteuil,  France.  The  Early  Argenteuil  was  developed 
in  1862  by  Louis  Lherault,  also  an  asparagus  grower  at  Argenteuil. 

Present  Day  Varieties  of  Asparagus  in  the  United  States. — It  is 
recognized  that  many  of  the  so-called  varieties  of  asparagus  differ 
but  little.  The  same  variety  may  present  characters  sufficiently 
different  when  grown  under  widely  different  environmental  conditions 
to  suggest  distinct  varietal  names. 

Conover's  Colossal  (Van  Sicklen,  Colossal). — This  variety  origi- 
nated with  Abraham  Van  Sicklen  of  Long  Island,  New  York,  and  was 
introduced  by  S.  B.  Conover,  a  commission  merchant  of  West  Wash- 
ington Market,  New  York  City,  about  1882.  It  is  the  oldest  known 
American  variety.  It  is  now  being  superseded  by  other  more  rust 
resistant  varieties  like  the  Palmetto  and  the  Washington  strains. 

Palmetto. — This  variety  was  introduced  by  Peter  Henderson  & 
Company  of  New  York,  N.  Y.,  in  1886.  It  originated  on  a  farm  in 
South  Carolina.  The  particular  advantages  of  Palmetto  are  its  resist- 
ance to  rust  and  its  productivity. 


BlJL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  69 

Columbian  Mammoth  White. — This  variety  was  introduced  by  D. 
M.  Ferry  &  Company  of  Detroit,  Michigan,  in  1893.  "It  was  the 
result  of  patient  work  and  careful  selection  of  the  progeny  of  a  single 
plant  having  white  shoots  found  growing  in  a  field  of  Conover's 
Colossal.  Seed  was  sown  from  this  plant,  a  small  percentage  of  which 
came  true,  and  these  were  planted  by  themselves  and  seed  from  them 
saved.  This  process  was  continued  for  a  period  of  fourteen  years 
preceding  the  dates  of  introduction.  At  the  present  time  only  a 
relatively  small  percentage  of  seeds  produced  green  plants." 
(Myers.(17))  This  variety  is  characterized  by  its  large  shoots,  which 
remain  a  clear  white  until  3  or  4  inches  above  ground. 

Reading  Giant. — This  is  an  old  variety  of  English  origin.  It  was 
formerly  grown  to  a  considerable  extent  in  the  eastern  states. 

Washington  Varieties. — The  Washington  varieties  are  very  promi- 
nent and  promising  American  sorts.  The  history  of  these  is  described 
by  J.  B.  Norton(18) : 

"Varieties  from  all  over  the  world  were  collected  at  Concord, 
Mass.,  and  subjected  to  rust-epidemic  conditions.  Not  one  plant  was 
found  to  be  completely  immune  to  rust.  However,  selections  were 
made  in  1908  from  the  most  resistant  ones  and  pedigreed  seed  pro- 
duced in  1909.  The  lots  of  seedlings  grown  in  1910  showed  one  male, 
A7-83,  from  a  lot  of  New  American  of  unknown  origin,  to  be  a  won- 
derful plant  in  transmitting  vigor  and  rust  resistance  to  the  progeny. 
A  female  plant,  B32-39,  from  Reading  Giant,  procured  from  Sutton  & 
Sons,  Reading,  England,  when  crossed  with  this  male  gave  the  best 
progeny  lot  of  all  the  hundreds  of  combinations.  From  this  pair  came 
our  first -named  strain,  Martha  Washington. 

'  ■  The  male  plant,  Washington,  and  the  female  plant,  Martha,  with 
other  female  plants,  have  since  been  removed  to  the  Arlington  Experi- 
mental Farm,  near  Washington,  D.  C,  the  crowns  being  separated 
into  several  divisions  and  planted  in  an  isolated  bed  for  breeding 
purposes.  Several  new  female  plants  have  been  added  from  time  to 
time  as  they  have  shown  their  value  as  producers  of  good  seedlings. 
Notable  among  these  is  the  giant  female  taken  as  a  seedling  from  a 
bed  of  Reading  Giant  grown  by  Mr.  C.  W.  Prescott,  at  Concord,  Mass., 
in  1910.  This  plant  has  been  named  Mary,  and  in  combination  with 
the  male  plant,  Washington,  gives  our  newest  named  strain,  Mary 
Washington. " 

In  Mary  Washington,  Norton  has  produced  a  variety  that  is  much 
more  uniform  in  size,  shape,  and  color  than  any  of  the  older  varieties. 
The  Washington  varieties  are  replacing  the  older  ones  in  almost  all 


70  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

asparagus  regions  which  are  subject  to  severe  rust  epidemics,  and  also 
in  some  asparagus  sections  where  the  rust  is  almost  unknown.  In  the 
northeastern  states  the  growers  favor  the  Martha  Washington,  but  in 
most  other  sections  the  Mary  Washington  is  the  more  popular  of  the 
two. 

Almost  all  asparagus  varieties  can  be  placed  in  two  groups  accord- 
ing to  the  color  of  the  spears :  The  varieties  with  light  green  spears, 
of  which  Conover's  Colossal  is  most  representative;  before  they  are 
exposed  to  the  light  the  spears  have  a  violet  or  reddish  tip.  The 
varieties  with  dark  green  spears  and  a  purplish  overcast;  these 
varieties  are  purple  tipped  before  they  are  exposed  to  the  light. 

Observation  seems  to  show  that  Palmetto  and  Argenteuil  are  very 
nearly  identical.  Some  growers  claim  that  Palmetto  has  spears  of  a 
deeper  purple  color,  is  longer  lived,  and  is  more  productive  than 
Argenteuil;  other  growers  claim  just  the  opposite.  Differences 
between  the  two  appear  to  be  due  to  soil  and  climatic  conditions  and 
to  methods  of  selection.  So  far  as  is  known,  no  pedigree  work  has 
been  done  on  the  Argenteuil  or  Palmetto  varieties  comparable  with 
that  done  by  Norton  on  Mary  Washington. 


SEED   PRODUCTION   AND    METHODS   OF    IMPROVEMENT 

Seed  Selection. — It  is  well  recognized  by  all  asparagus  growers  that 
large,  plump,  glossy,  and  fully  matured  seed  is  superior  to  small, 
shrivelled,  dull,  and  immature  seed.  However,  the  methods  of  grow- 
ing asparagus  seed  of  high  quality  have  not  been  given  the  attention 
that  they  deserve. 

Age  of  Plant  from  Which  to  Select  Seed. — There  is  a  diversity  of 
opinion  among  growers  as  to  what  the  ages  of  plants  should  be  in 
order  to  yield  seed  of  the  best  quality.  The  statement  is  made  by  some 
that  plants  must  be  "not  less  than  four  years  old"  before  they  have 
sufficient  maturity  and  vigor  to  produce  seed  of  high  quality.  Other 
growers  state  that  seed  should  be  harvested  only  from  plants  the 
crowns  of  which  were  planted  the  previous  year.  Plants  of  this  age, 
it  is  reasoned,  have  not  been  " weakened' '  by  the  harvesting  of  sprouts 
during  the  current  year  as  have  the  older  plants;  "consequently,  it 
has  been  possible  for  more  energy  to  be  directed  to  the  production  of 
seed."  It  is  a  common  practice  on  California  asparagus  farms  to  cut 
market  asparagus  for  a  period  of  about  three  or  four  weeks  the  first 
year  after  transplanting ;  whereas,  in  older  beds,  the  cutting  season  is 
for  a  much  longer  period.    Hence,  in  the  former  case,  there  is  a  longer 


BUL.  446]  THE    ASPARAGUS    INDUSTRY    IN    CALIFORNIA  71 

season  of  growth  after  the  cutting  period  than  in  the  older  beds.  It 
is  reasoned  that  seed  from  plants  which  have  been  cut  for  a  few 
weeks  only  will  have  a  better  opportunity  to  fill  out  and  mature.  It 
should  be  stated  also  that  by  taking  seed  from  young  asparagus  beds 
rather  than  from  old  ones,  the  grower  has  a  better  opportunity  to  make 
rapid  improvement  in  his  varieties.  Other  growers  claim  that  there 
is  no  correlation  between  the  age  of  the  mother  plant  and  the  vigor  of 
the  seed  it  produces. 

Unfortunately,  there  are  no  reliable  experimental  data  which  will 
enable  us  to  discuss  authoritatively  the  three  views  presented  above 
and  to  make  a  definite  recommendation  as  to  the  best  age  of  plants 
from  which  to  select  seed. 

Quality  of  Seed  from  Different  Parts  of  the  Plant. — Some  hold  the 
opinion  that  seeds  borne  on  different  parts  of  the  same  plant  vary  in 
quality.  It  is  stated  that  the  best  seed  is  procured  from  the  lower 
part  of  the  plant  and  that  consequently  it  is  advisable  to  top  it  by 
removing  from  8  to  12  inches,  after  the  basal  flowers  have  been 
fertilized.  The  first  flowers  to  open  and  the  first  berries  to  form  are 
on  the  main  shoot  near  the  base  of  the  plant ;  and  on  the  whole  plant, 
or  on  any  one  branch,  the  order  of  maturing  of  berries  is  from  the  base 
to  the  apex.  At  the  tips  of  the  branches,  then,  there  may  be  at  harvest 
time  a  considerable  number  of  berries  which  are  not  so  well  developed 
as  those  farther  down  on  the  branches  and,  consequently,  the  har- 
vested seed  may  contain  a  certain  percentage  of  seed  from  relatively 
immature  berries.  It  is  believed  that  this  condition  can  be  obviated  by 
cutting  back  the  tops  after  the  basal  flowers  have  been  fertilized.  It  is 
also  asserted  that  topping  the  plants  leaves  more  nourishment  avail- 
able for  the  remaining  seeds,  and  that  they  will  thereby  become  larger 
and  produce  more  vigorous  seedlings. 

Since  no  carefully  conducted  tests  have  been  made  to  ascertain  the 
value  of  the  practice  of  cutting  back  the  tops  of  seed-bearing  plants, 
the  authors  are  not  in  a  position  either  to  recommend  or  to  discourage 
this  practice.  Careful  screening  and  grading,  however,  should  elimi- 
nate the  smaller  and  less  mature  seeds  which  are  borne  near  the  tops 
of  the  branches.  Grading  is  suggested  as  being  a  possible  and 
desirable  substitute  for  topping. 

Methods  of  Handling  for  Seed  Production. — The  commercial 
grower  who  is  producing  his  own  seed  should  observe  some  of  the 
fundamental  principles  of  selection.  In  most  of  our  crops,  both  male 
and  female  reproductive  organs  occur  on  the  same  plant  and  usually 
in   the    same    flower,    but    each    asparagus   plant   we    have    seen    is 


72  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

almost  always  of  one  sex  only.  It  is  as  important  to  choose  the  best 
male  plants  as  it  is  to  select  productive,  healthy,  and  otherwise 
desirable  types  of  female  plants.  In  the  past,  practically  the  only 
method  of  seed  selection  used  by  the  growers  themselves  has  been  to 
go  through  the  fields  in  the  fall  of  the  year  when  the  seeds  are  mature 
and  harvest  the  seed  from  the  desirable  seed-bearing  plants.  The  chief 
weakness  of  this  method  is  that  the  female  parent  only  is  selected. 
The  flowers  of  these  female  plants  may  have  been  pollinated  by 
inferior  or  mediocre  male  plants. 

The  improvement  of  asparagus  by  seed  selection  is  an  attractive 
undertaking  and  will  prove  profitable  if  done  properly.  Several 
methods  are  given  below. 

Method  1. — Records  of  the  performance  of  certain  promising  indi- 
vidual crowns  should  be  kept  over  a  period  of  several  years,  The 
crowns  of  the  most  desirable  male  and  female  plants  should  be  dug 
and  set  together  in  a  bed  that  is  isolated.  One  male  plant  to  about 
five  or  six  females  is  sufficient.  It  is  best  to  group  the  female  plants 
about  the  male.  The  desirable  female  plants  will  be  pollinated  only 
by  the  selected  male  or  males. 

Method  2. — In  the  commercial  field,  a  number  of  the  most  desir- 
able male  and  female  individual  plants  should  be  marked  in  the  ratio 
of  approximately  one  male  to  five  or  six  females.  These  individuals 
should  be  allowed  to  mature  before  the  main  crop,  so  that  pollination 
is  only  between  the  individuals  selected.  This  method,  however,  is 
not  practicable  in  regions  where  the  ridges  are  disked  or  plowed  down 
periodically  to  loosen  the  soil  and  destroy  the  weed  growth. 

Method  3. — A  small  isolated  acreage  should  be  set  aside  for  seed 
production  only.  At  the  beginning  of  the  blossoming  period  the 
grower  should  grub  out  weak  and  undesirable  types  of  male  plants. 
If  they  are  left  in  the  field,  pollen  from  them  may  be  carried  to  the 
flowers  of  the  selected  female  plants  and  the  undesirable  characters 
of  the  inferior  males  transmitted  to  the  progeny  of  the  superior 
females.  Seed  from  the  superior  females  only  should  be  harvested. 
It  is  unnecessary  to  grub  out  the  inferior  females,  the  seed  of  which 
should  not  be  harvested. 

In  careful  breeding  work,  however,  hand  pollination  is  necessary 
if  the  best  results  are  to  be  obtained.  Even  when  plants  are  isolated 
it  is  not  always  safe  to  conclude  that  foreign  pollen  has  not  been 
introduced. 

Open  Pollination. — Regarding  open  pollination,  Norton  states  that 
"the   insect   visitors   to   the   asparagus  flowers   are   largely   bees   of 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  73 

different  kinds.  The  honey  bee  is  most  plentiful  during  the  blooming 
season,  and  at  this  time  of  the  year  practically  all  of  the  pollen  that 
comes  into  hives  that  are  near  the  asparagus  fields  is  the  rich,  orange 
pollen  from  the  staminate  asparagus  flowers.  Apparently  a  large 
amount  of  nectar  is  also  produced.  This  is  shown  particularly  in 
flowers  under  bags  where  the  bees  have  been  kept  away  until  the 
flower  is  old,  when  it  is  so  abundant  as  to  interfere  with  pollination. 
Some  of  these  small  bees  are  a  nuisance  in  the  pollination  work, 
apparently  being  especially  attracted  by  the  extra  quantity  of  honey 
in  the  protected  flowers. 

"The  wind  seems  to  play  little  part  in  pollination,  as  the  male 
flowers  retain  their  load  of  pollen  until  they  begin  to  wither,  unless 
it  is  removed  by  a  bee.  The  pollen  hangs  together  in  masses  and  does 
not  become  powdery  until  the  flower  dries  up." 

Testing  of  Progeny. — The  progeny  of  the  various  crosses  and 
selections  should  be  tested  under  field  conditions ;  only  those  com- 
binations giving  desirable  offspring  should  be  retained  for  future 
breeding. 

Desirable  Types  to  Select  for  Breeding  Purposes. — As  much  care 
should  be  given  to  the  selection  of  the  male  as  to  the  female  parent. 
The  plants  should  be  heavy  producers  throughout  the  cutting  season 
and  over  a  long  period  of  years.  The  spears  should  not  bulge  just 
below  the  surface  of  the  soil;  they  should  have  a  gradual  taper  from 
butt  to  tip.  The  leaves  or  scales  should  fit  snugly  against  the  stem 
and  should  remain  compressed  against  it  for  some  time  after  coming 
through  the  soil.  The  color  should  be  a  dark  green  with  a  purple  over- 
cast. The  dark  green  varieties  appear  to  be  more  rust  resistant  than 
those  that  are  of  a  lighter  color. 

Selection  of  the  plants  for  breeding  purposes  after  the  stalks  have 
become  fully  developed  is  not  as  desirable  as  selection  during  the 
cutting  season.  Plants  with  high-branching  stalks  produce  spears 
that  hold  the  scale  leaves  close  for  a  time.  It  is  better  to  select  plants 
that  have  a  medium  number  of  large  healthy  stalks  than  those  that 
have  a  large  number  of  small  stalks.  Some  authors  state  that  those 
pistillate  plants  which  bear  much  seed  are  not  as  vigorous  or  as  heavy 
yielders  of  marketable  spears  as  those  which  produce  few  seeds.  They, 
therefore,  recommend  using  for  breeding  purposes  pistillate  plants 
that  do  not  naturally  produce  a  large  number  of  flowers.  So  far  as  is 
known,  no  experiments  have  been  conducted  to  test  this  theory. 

Harvesting  and  Grading  Seed. — If  the  berries  are  harvested  before 
they  are  mature,  the  seed  shrivel  to  some  extent.     At  maturity  the 


74  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

selected  seed-bearing  plants  are  cut  and  laid  on  canvas,  and  the 
berries  may  be  placed  in  burlap  sacks  and  pounded  or  tramped  in 
order  to  break  the  berry  coats  and  free  the  seed.  This  mass  of 
material  is  then  placed  in  a  barrel  or  tank  of  water  and  stirred  well. 
The  seeds  settle  to  the  bottom  and  the  lighter  material,  such  as  skins, 
pulp,  and  stems,  rise  to  the  surface,  where  they  are  skimmed  or  floated 
off.  After  several  changes  of  water,  the  seed  should  be  spread  out  on 
a  canvas  to  dry. 

After  the  seed  is  dried,  it  should  be  run  over  properly  meshed 
screens  and  graded  as  to  size.  The  practice  of  grading  is  strongly 
recommended. 

There  is  much  variation  in  the  weight  and  number  of  seed  to  the 
pound  in  different  lots  of  commercial  asparagus  seed.  Certain  lots  of 
seed  contain  as  many  as  28,000  seeds  to  the  pound,  while  others  have 
approximately  19,000  seeds.  The  average  run  of  commercial  seed, 
however,  has  about  22,000  seeds  to  the  pound.  It  is  well  known  that 
Mary  Washington  seeds  are  of  larger  size  than  those  of  any  other 
variety,  which  favors  early  seedling  development  and  large  one-year- 
old  crowns.  There  are  a  number  of  factors  which  influence  the  size 
of  seed,  but  most  lots  of  seed  may  be  improved  by  careful  grading. 

Seed  Storage  and  Viability. — Asparagus  seed  should  be  stored  in 
a  cool,  dry  place.  Under  proper  storage  conditions  it  will  maintain 
its  viability  for  four  or  five  years.  However,  it  is  best  to  plant  fresh 
seed,  as  it  germinates  more  quickly  than  old  seed. 


FRESH    ASPARAGUS   FROM   THE    FIELD   TO    MARKET 

Fresh  asparagus  may  be  sold  with  the  spears  entirely  blanched, 
almost  entirely  blanched  (green  tip),  green  throughout  except  for 
white  butts,  or  entirely  green.  White  asparagus  is  produced  by  growth 
in  the  dark.  When  exposed  to  the  light  the  spears  become  green  because 
of  the  development  of  the  chlorophyll  pigment.  The  longer  the  time  the 
spears  are  permitted  to  grow  above  ground  before  cutting,  the  greater 
will  be  the  percentage  of  green  on  the  harvested  product.  In  Europe, 
nearly  all  of  the  asparagus  sold  in  the  fresh  condition  is  white.  In 
some  parts  of  the  east  asparagus  beetles  do  considerable  damage  to 
the  spears  after  they  appear  above  ground;  hilling  and  cutting  the 
white  product,  therefore,  greatly  reduce  the  loss  from  injury.  The 
greatest  demand  in  this  country  at  present  is  for  the  green  product, 
and  the  demand  for  this  type  is  constantly  becoming  greater.  Most 
of  the  asparagus  districts  in  the  United  States  ship  the  green  product. 


BlIL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  75 

A  white  butt  is  desired  by  most  shippers  as  they  claim  the  spears 
wilt  less  than  when  green  and  tender  throughout.  In  the  Delta  most 
of  the  asparagus  is  cut  for  the  market  before  April  10.  Some  growers, 
however,  cut  during  the  entire  season,  that  is,  up  to  about  July  1,  to 
supply  the  local  markets.  In  the  Imperial  Valley,  the  aim  is  to 
terminate  the  main  shipping  season,  prior  to  the  appearance  of  large 
quantities  of  asparagus  grown  nearer  the  main  consuming  centers. 
When  harvesting  commences  in  the  east  and  middle  west,  long  dis- 
tance shipments  may  be  fewer,  though  California  asparagus  is  often 
sold  profitably  in  competition  with  early  receipts  from  the  Carolinas 
and  Georgia, 

Cutting. — The  manner  of  cutting  asparagus  varies  considerably  in 
different  sections.  According  to  Loisel,(14)  two  methods  of  harvesting 
are  used  in  France :  In  the  small  gardens  the  soil  is  removed  to  some 
depth  and  the  spear  is  given  a  twist,  which  severs  it  at  its  points  of 
attachment  to  the  crown.  When  the  spears  have  been  removed,  the 
mound  is  again  rebuilt.  The  method  is  fairly  rapid  in  working  with 
the  lighter  types  of  soil.  It  also  has  the  advantage  of  causing  no 
injury  to  the  young  spears  which  are  not  in  sight.  The  more  common 
method  is  to  cut  the  spears  with  a  gouge  knife  very  similar  to  the  fish- 
tailed  and  chisel-shaped  asparagus  knives  used  in  this  country. 

In  the  Imperial  Valley  an  effort  is  made  to  secure  as  much  green 
as  possible  and  still  have  spears  with  closed  heads  that  will  carry 
well  to  the  eastern  and  middle  western  markets.  Only  a  low  ridge 
is  made  over  the  asparagus  row  to  mark  it  and  prevent  flooding  at 
time  of  irrigation. 

In  the  California  Delta,  the  spears  are  cut  when  they  are  3  to  4 
inches  above  ground.  There  is  constant  danger  of  frost  during  the 
early  season;  in  order  to  prevent  a  great  deal  of  loss,  therefore,  the 
asparagus  is  usually  cut  with  less  green  than  is  the  practice  in  most 
of  the  other  green  "grass"  districts. 

At  the  beginning  of  the  season  when  the  harvest  is  light,  the 
cutters  carry  the  spears  in  containers  and  place  them  in  lug  boxes  at 
the  ends  of  the  rows.  When  production  becomes  heavier,  however,  the 
asparagus  is  laid  on  the  tops  of  the  ridges,  the  harvest  from  six  to 
eight  rows  usually  being  laid  on  the  two  center  ridges. 

In  the  Delta  the  cutters  are  usually  in  the  field  at  daybreak. 
Cuttings  are  made  whenever  the  spears  are  sufficiently  long ;  this  may 
necessitate  harvesting  each  day,  or  every  second  or  third  day.  Cutting 
continues  until  all  the  fields  have  been  gone  over.  In  the  San  Fernando 
Valley  of  California  and  in  some  sections  of  the  Middle  West  the  fields 


76  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

are  often  cut  twice  in  a  day,  especially  on  light  sandy  loam  soils  after 
a  warm  rain  and  following  hot  nights.  On  heavy  clay  soils,  the  growth 
is  often  so  slow  that  cuttings  are  made  but  once  or  twice  a  week. 

Hauling. — The  cut  spears  which  have  been  laid  on  the  ridges  are 
gathered  and  placed  in  a  horse-drawn  sled  or  cart  (fig.  29).  If  the 
packing  is  to  be  done  in  the  field,  the  spears  are  usually  stacked  loosely 
in  the  body  of  the  cart,  with  the  heads  touching  the  sloping  front.  If 
the  packing  is  to  be  done  at  a  distance  from  the  field,  the  asparagus 
is  usually  placed  in  lug  boxes.    These  are  then  stacked  at  the  ends  of 


Fig.  29. — Cart  used  in  hauling  asparagus  from  the  field  to  the  washing  shed. 

the  rows  or  are  placed  on  loading  platforms,  from  which  they  are 
hauled  by  auto  trucks  directly  to  the  packing  sheds  or  to  the  wharves 
and  later  taken  to  the  packing  sheds  by  boat. 

Types  of  Pack. — Fresh  asparagus  may  be  packed  loose  in  the 
crate  or  bunched.  The  loose  pack  may  include  the  ordinary  ungraded 
field  run  of  asparagus  or  only  the  spears  that  are  difficult  to  bunch. 

The  Loose  Pack. — Shippers  of  loose-pack  asparagus  usually  have 
their  own  packing  sheds  in  the  field,  and  the  asparagus  is  hauled 
directly  from  the  field  into  the  shed.  The  spears  are  laid  straight  in  a 
form  about  3  feet  wide,  2  to  3  feet  high,  and  about  10  inches  deep  (fig. 
30).  The  tips  rest  against  the  back  wall  of  the  form.  A  board  moving 
vertically  in  a  slot  is  pressed  down  and  locked  to  hold  the  spears 
firmly  in  place.     These  are  then  trimmed  to  a  uniform  length  with  a 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


77 


large  knife,  which  is  usually  made  from  an  old  cross-cut  saw.     The 
spears  are  trimmed  to  a  length  of  9  or  10  inches  or  less. 

After  trimming,  the  spears  are  laid  loose  in  pyramid-shaped  crates 
without  partitions  (fig.  31).  Oiled  paper  is  placed  on  the  bottom  and 
two  sides  of  the  box.  On  the  paper  in  the  bottom  of  the  box  is  placed 
a  layer  of  wet  moss.  Then,  a  thin  galvanized  tin  sheet,  or  wooden 
panel,  having  the  dimensions  of  the  bottom  of  the  box  and  equipped 


Fig.  30. — Trimming  asparagus  in  the  field  shed. 

with  a  handle,  is  laid  on  top  of  the  moss.  During  packing,  the  crate 
is  laid  on  its  side.  After  the  box  has  been  filled,  the  tin  sheet  is 
jerked  out,  leaving  the  asparagus  butts  resting  upon  the  wet  moss.  The 
oiled  paper  is  then  folded  over  the  asparagus  on  the  open  side  and 
the  side  boards  nailed  on.  Sufficient  asparagus  is  placed  in  the  box 
to  give  a  good  bulge;  this  prevents  movement  of  spears  within  the 
container  and  holds  the  pack  firm  even  if  the  spears  become  slightly 
wilted. 

Bunched  Asparagus. — By  far  the  greater  proportion  of  asparagus 
which  is  shipped  to  the  markets  is  first  carefully  graded,  then  bunched, 


78 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


trimmed,  wrapped  and  packed.  Well-equipped  packing  houses  are 
provided  for  these  operations,  and  some  of  the  larger  employ  several 
hundred  workers  during  the  height  of  the  shipping  season. 

Sorting  and  Grading. — Asparagus  is  brought  to  the  packing  shed 
usually  in  50  or  60-pound  lug  boxes.  Here  the  spears  are  laid  on 
tables  and  sorted  by  hand  into  different  grades.  California  shippers 
usually  pack  four  or  five  different  grades,  which  are  distinguished 
mainly  on  the  basis  of  size.  In  addition  to  these  there  is  another  grade 
Avhich  includes  all  spears  too  crooked  to  fit  in  the  bunch  and  those 


Fig.  31. — This  shows  the  manner  of  making  the  loose  pack. 

that  are  not  green  enough.  These  are  not  bunched,  but  are  packed 
loose,  usually  in  50  or  60-pound  lug  boxes  or  pyramidal  crates,  and 
nearly  always  shipped  to  the  local  markets  only. 

The  following  grades  and  specifications  for  asparagus  have  been 
adopted  by  the  Bureau  of  Agricultural  Economics  of  the  United  States 
Department  of  Agriculture : 

I  J.  S.  Grade  No.  1  shall  consist  of  clean,  fresh  stalks  of  asparagus 
which  are  not  wilted  or  crooked,  which  do  not  show  broken  or  spread- 
ing tips,  and  which  are  free  from  damage  caused  by  disease,  insects, 
or  mechanical  means.  (As  used  in  U.  S.  Grade  No.  1  and  No.  2,  "free 
from  damage"  means  that  the  asparagus  shall  not  be  injured  to  an 
extent  readily  apparent  upon  examination.)     In  order  to  allow  for 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


79 


variations  incident  to  proper  grading  and  handling,  not  more  than 
10  per  cent,  by  count,  of  any  lot  may  be  below  the  requirements  of 
this  grade  but  not  to  exceed  one-half  of  this  tolerance  shall  be  allowed 
for  any  one  defect. 

U.  S.  Grade  No.  2  shall  consist  of  stalks  which  do  not  meet  the 
requirements  of  the  foregoing  grade. 


Fig.  32. — One  type  of  asparagus  buncher.     Other  types  are  in  the  market. 


Fig.  33. — Five  common  grades  of  green  asparagus.     From  left  to  right: 
Colossal,  Extra  Selected,  Extra  Fancy,  Fancy,  and  Choice. 


In  addition  to  the  statement  of  grade,  any  lot  of  asparagus  may 
be  classified  as  Small,  Medium,  or  Large,  if  80  per  cent,  by  count,  of 
the  stalks  in  any  lot  conform  to  the  following  requirements  for  such 

Vie  to  %  inch  diameter;  Large, 


sizes:  Small,  %  to  %6  inch;  Medium,  ° 


over  %  inch.     The  foregoing  measurements  refer  to  the  diameter  of 
the  spears  measured  at  a  point  not  more  than  8  inches  from  the  tip. 


80 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Bunching. — The  different  grades  of  spears  are  tied  in  bunches, 
each  weighing  approximately  2%  pounds.  When  placing  the  spears 
in  the  buncher,  care  is  exercised  to  have  the  top  of  the  bunch  even 
and  the  curved  tips  pointing  inward.  The  bunches  are  bound  tightly 
by  hand  near  the  base  and  tip.  The  tape  used  generally  comes  on 
1,000-foot  spools,  is  ^-inch  wide,  and  before  using  is  run  onto  a 
cylinder  and  then  cut  into  18-inch  lengths.  Different  colors  of  tapes 
are  often  used  to  designate  the  various  grades. 

There  are  sometimes  complaints  on  the  eastern  markets  that  the 
bunches  are  loose  when  they  arrive.     This  condition  may  be  due  to 


Fig.  34. — Green  asparagus,  bunched  and  ready  for  shipment. 


high  temperatures  which  increase  transpiration  and  cause  a  pro- 
nounced wilting  of  the  spears.  However,  there  are  instances  where 
bunches  reach  the  market  in  a  loose  condition,  and  yet  the  individual 
spears  are  still  turgid.  This  is  due  to  the  following  conditions :  Early 
in  the  season  when  the  weather  is  cool  and  moist,  the  asparagus  shoots 
brought  in  from  the  field  in  the  early  morning  are  very  turgid.  If 
they  are  bunched  in  this  condition,  it  is  difficult  to  obtain  a  snug  fit 
of  spears  in  the  bunch.  Although  the  bunch  may  be  firmly  tied,  the 
necessary  handling  and  jostling  in  packing  and  shipping,  together 
with  even  a  slight  loss  of  water,  brings  about  a  readjustment  of  the 
position  of  the  spears  in  the  bunch.  If  the  spears  are  bunched  when 
they  are  slightly  wilted  and  pliable,  a  tight  pack  can  be  secured ;  and 
they  are  not  so  easily  broken  when  being  tied.     When  these  bunches 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  81 

are  later  stood  on  moist  moss  they  absorb  water,  become  slightly  more 
turgid,  and  remain  so. 

Trimming. — After  they  are  tied,  the  bunches  are  trimmed  to  a 
uniform  length,  usually  of  81/*?  inches.  Trimming  is  done  by  hand 
with  the  aid  of  a  long-bladed  knife.  The  trimmed  bunches  are 
immediately  stood  in  shallow  pans  in  an  inch  or  two  of  water,  which 
is  usually  iced.  Here  they  remain  until  packed.  The  trimmed  butts 
from  green  asparagus  may  constiute  a  waste  of  5  to  40  per  cent.  At 
present  no  use  is  made  of  the  trimmings. 

Packing. — The  bunches  are  removed  from  the  pans  and  each 
wrapped  in  a  parchment  paper  label,  usually  measuring  about  8  inches 
wide  and  18  inches  long.  The  tips  of  the  asparagus  shoots  extend 
above  the  edge  of  the  label.  The  wrapped  bunches  are  immediately 
packed  in  the  pyramidal  crates  with  the  butts  resting  on  moist  moss. 
It  is  the  practice  to  place  parchment  paper  in  the  bottom  of  the  box, 
so  that  the  moss  rests  upon  this  paper,  rather  than  upon  the  dry 
boards  of  the  box.  This  practice  also  prevents  the  rapid  evaporation 
of  water  from  the  moss. 

The  moss  is  obtained  in  bale  lots.  It  is  shredded  by  hand  or  with 
a  hair  picker  operated  by  man  power.  About  one-half  pound  of  wet 
moss  is  placed  in  each  crate. 

When  the  packer  receives  the  crate  it  is  " mossed"  and  open  on 
one  side.  When  packed,  the  sides  are  nailed  on  so  that  the  label  of 
each  bunch  is  conspicuous  and  the  tips  show  above  the  upper  strip. 

Crates  Used  for  Packing. — Nearly  all  California  asparagus  is 
shipped  in  pyramidal  crates.  It  is  possible  in  a  crate  of  this  type  to 
have  the  bunches  standing  upright  while  being  shipped.  The  shape  of 
the  box  conforms  to  the  tapering  form  of  the  bunches,  and,  when  well 
packed,  the  asparagus  has  little  opportunity  to  move  about.  The  crate 
is  divided  into  two  compartments,  each  holding  six  2%-pound  bunches. 

In  the  California  pyramidal  crate,  the  two  end  boards  are  10% 
inches  high  and  %  inch  thick,  9%  inches  wide  at  the  top  and  11  inches 
wide  at  the  bottom ;  the  partition  board  is  only  %g  inch  thick ;  the  top, 
bottom  and  side  board  are  %  inch  thick;  the  top  boards  are  4  by 
19V2  inches;  the  bottom  boards,  5%  by  19%  inches;  and  the  sides 
(upper)  2  by  19%  inches,  and  (lower)  3%  by  19%  inches;  two  cleats 
on  the  top  are  %  by  9%  by  %  inches. 

The  two  compartment  pyramidal  crate  is  also  used  in  South 
Carolina.  In  New  Jersey,  the  32-quart  berry  crate  holding  24  bunches 
is  used.  In  Illinois  a  sectional  crate  is  in  use  with  individual  compart- 
ments for  24  bunches. 


82  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Precooling ,  Loading,  and  Refrigeration. — In  the  early  spring 
when  cuttings  are  light  and  before  it  is  possible  to  obtain  a  sufficient 
number  of  crates  to  make  carlot  shipments,  almost  all  of  the  asparagus 
is  shipped  by  express  and  without  refrigeration.  In  the  Imperial 
Valley,  as  soon  as  carlot  shipments  begin,  the  asparagus  is  precooled 
before  it  is  loaded  into  iced  cars.  In  Northern  California,  precooling 
is  not  practiced,  the  crates  being  loaded  into  iced  Pacific  Fruit 
Express  cars  as  soon  as  packed.  The  crates  are  stacked  in  tiers  in 
the  car  and  held  stationary  by  bracing.  Bunker  icing  is  practiced. 
The  bunkers  are  filled  with  ice  several  times  during  transit. 

Shipping  Seasons. — The  shipping  season  of  any  locality  varies  from 
year  to  year.  Temperature  is  the  main  factor  determining  the  begin- 
ning of  the  harvesting  season.  California  is  the  first  state  to  start 
shipping  asparagus  in  early  spring.  The  Delta  region  and  the  Imperial 
Valley  start  shipping  about  the  same  time.  Asparagus  is  shipped  from 
the  Imperial  Valley  until  eastern  asparagus  moves  in  quantity.  This 
may  be  as  late  as  May  1,  but  is  usually  about  the  middle  of  April. 
There  is  no  canning  of  asparagus  in  the  Imperial  Valley  or  about  Los 
Angeles.  Most  of  the  growers  in  the  Delta  stop  cutting  for  shipment 
by  April  1,  or  shortly  thereafter.  Heavy  rains  in  late  March  or 
early  April  may  delay  the  opening  of  the  canning  season.  There  is 
a  considerable  acreage,  however,  that  is  cut  for  shipment  to  nearby 
markets  throughout  the  season,  i.e.,  until  late  in  June  or  early  in 
July.  South  Carolina  and  adjoining  states  usually  start  shipping 
a  small  quantity  of  asparagus  in  less  than  carlots  in  March.  Most 
of  the  asparagus,  however,  moves  from  these  states  in  April  and  May. 
Illinois  starts  shipping  in  April  and  continues  throughout  the  months 
of  May  and  June.  New  Jersey  also  starts  shipping  in  April,  though 
the  bulk  of  the  crop  moves  during  May  and  June.  New  Jersey  also 
ships  a  small  amount  in  early  July,  as  does  also  California  and  Illinois. 

Carlot  Shipments.- — Carlot  shipments  of  asparagus  by  states  may 
be  obtained  from  the  Bureau  of  Agricultural  Economics  of  the  United 
States  Department  of  Agriculture.  The  figures,  however,  do  not  show 
the  amount  of  asparagus  grown  near  the  large  consuming  centers  and 
hauled  to  market  by  truck.  Much  asparagus  grown  in  the  vicinity  of 
New  York,  especially  on  the  New  Jersey  side,  and  in  the  neighborhood 
of  Boston,  Baltimore,  Philadelphia,  Washington,  D.  C,  Chicago,  Los 
Angeles,  and  other  large  cities  is  hauled  to  market  by  auto  trucks  and 
therefore  does  not  appear  in  the  carlot  totals.  The  apparent  gradual 
decrease  in  the  amount  shipped  from  New  Jersey  is  due  primarily  to 
the  increasing  volume  being  transported  by  truck. 


BUL.  446 J  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  83 

Most  of  the  carlot  shipments  in  California  are  from  the  Delta 
region.  The  grading  and  packing  sometimes  is  done  on  the  ranches, 
but  usually  it  is  done  in  the  more  densely  populated  centers  where 
there  is  more  labor  available.  Formerly  most  of  the  asparagus  grown 
in  the  Imperial  Valley  was  shipped  to  Chicago.  The  early  ship- 
ments from  the  Delta  go  principally  to  the  large  eastern  markets. 
In  March  the  product  is  pretty  well  distributed  throughout  the 
Middle  West  and  East,  but  when  the  eastern  beds  start  bearing,  the 
product  from  the  Delta  goes  primarily  to  points  in  California  and 
other  coastal  and  Rocky  Mountain  states.  Most  of  the  asparagus 
produced  in  the  Los  Angeles  district  is  consumed  locally. 

Changes  in  the  Quality  of  Asparagus-  after  Cutting.— Bisson, 
Jones,  and  Robbins(n  have  shown  that  changes  occur  in  the  structure 
and  chemical  composition  of  asparagus  after  it  is  harvested  which 
affect  its  edible  qualities.  The  principal  changes  concern  growth  in 
length,  and  weight  of  dry  matter,  reducing  substances,  total  sugars, 
and  crude  fiber.  These  changes  are  markedly  influenced  by  the 
temperature  at  which  the  spears  are  stored. 

Asparagus  spears  grow  in  length  in  the  crate,  if  the  butts  are  on 
moist  moss.  If  the  moss  remains  moist  the  chief  factor  determining 
the  growth  rate  is  temperature.  The  growth  rate  was  found  to  be 
least  at  33°  F,  and  to  increase  as  the  temperature  is  raised  (within 
the  limits  of  the  experiment).  The  greatest  percentage  of  increase 
in  the  length  of  asparagus  occurred  the  first  24  hours,  after  which 
there  was  a  slowing  down  in  the  rate.  Mold  appeared  on  the  asparagus 
stored  at  temperatures  of  77°  F  and  95°  F  after  a  few  days,  and  these 
samples  were  therefore  discarded. 

Asparagus  spears  stored  with  their  butts  in  water  or  on  wet  moss 
absorb  water  and  increase  in  weight.  The  rate  of  weight  increase 
due  to  water  absorption  was  least  at  33°  F,  somewhat  greater  at  41°  F, 
and  still  greater  at  the  higher  temperatures.  Here,  again,  the  highest 
percentage  of  increase  in  weight  occurred  the  first  24  hours  after  the 
spears  were  harvested.  There  is  a  slight  wilting  immediately  after 
harvest,  which  no  doubt  accounts  to  some  extent  for  the  rapid  increase 
in  weight  during  the  early  storage  period. 

There  is  a  loss  in  reducing  substances  and  in  total  sugars  from  the 
spears  at  all  temperatures.  These  losses  are  especially  pronounced  at 
the  higher  temperatures  (56°,  77°,  and  95°),  the  maximum  rate  of 
loss  being  during  the  first  24  hours.  It  should  be  stated  that  the  sugars 
constitute  but  one  group  of  substances  which  determine  flavor ;  among 
others  may  be  mentioned  esters,  glucosides,  amino-acids,  and  proteins. 


84  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

The  loss  of  sugars  during  storage  is  due  to  its  destruction  in  respir- 
ation, and  its  transformation  to  cell  wall  material,  chiefly  lignin,  and 
other  substances. 

Both  microchemical  and  macrochemical  studies  showed  a  general 
increase  in  the  number  of  lignified  elements  both  in  the  fiber  zone  and 
in  the  vascular  bundles  of  the  spears  at  all  storage  temperatures. 
Lignification  took  place  the  full  length  of  the  spear.  The  percentage 
of  crude  fiber  was  determined  by  chemical  analysis.  The  greatest 
increase  in  crude  fiber  came  the  first  24  hours  after  the  asparagus  was 
cut,  but  was  least  at  the  lowest  temperature  and  greatest  at  the  highest 
temperature.  The  amount  of  crude  fiber  present  is  an  indication  of 
the  toughness  of  the  spear. 

Green  asparagus  should  be  bunched  and  packed  as  soon  after 
harvest  as  is  compatible  with  efficient  handling.  It  should  then  be 
placed  and  held  at  a  temperature  slightly  above  the  freezing  point. 
Even  at  this  low  temperature  there  is  some  deterioration  as  shown  in 
the  reduction  in  sugar  and  increase  in  fiber.  It  is  desirable  that  the 
product  reach  the  consumer  in  the  shortest  possible  time.  It  is 
advised  that  the  crate,  and  the  parchment  wrapper  about  the  indi- 
vidual bunches,  be  marked  in  some  way  to  indicate  to  retailers  and 
consumers  that  the  contents  be  kept  at  a  Ioav  temperature  in  order 
that  the  edible  quality  may  be  retained. 


THE   ASPARAGUS   CANNING    INDUSTRY 

II.  Hickmott  built  the  first  large  asparagus  cannery  in  the  United 
States  on  Bouldin  Island,  in  the  Delta  of  California,  three  miles 
southwest  of  Isleton,  in  1892. 

In  1899,  The  Golden  State  Asparagus  Company  was  organized. 
This  company  was  established  first  on  Grand  Island  opposite  Walnut 
Grove,  but  in  1904  moved  to  Isleton,  where  it  is  still  operating.  Since 
1900,  a  number  of  asparagus  canneries  have  been  constructed  along 
the  network  of  waterways  of  the  Delta.  By  1902,  there  were  six 
canneries  in  the  Delta,  chiefly  for  asparagus,  and  in  1924,  twenty 
canneries  were  packing  asparagus. 

The  Asparagus  Canning  Regions  of  California. — The  Sacramento 
and  San  Joaquin  valleys  are  the  only  regions  of  the  state  in  which 
asparagus  is  grown  for  canning.  The  soil  of  the  Delta,  particularly, 
is  well  adapted  to  the  growing  of  canning  asparagus,  most  of  it  being 
peat  or  muck,  mixed  with  a  small  amount  of  sediment.  This  sediment 
was  formerly  deposited  over  the  land  by  the  overflowing  rivers.     The 


BUL.  446]  THE   ASPARAGUS   INDUSTRY    IN    CALIFORNIA  85 

soil  is  so  light  and  porous  that  the  spears  will  grow  through  15  to  18 
inches  of  it  and  remain  perfectly  straight. 

Cutting  Season. — In  California,  the  canning  season  usually  starts 
about  April  1.  The  fields  are  usually  cut  until  late  in  June,  making 
the  cutting  season  for  white  asparagus  from  12  to  14  weeks. 

Preparatory  Tillage. — After  the  green  asparagus  season  is  over, 
the  low  ridges  are  disked  down  to  destroy  the  weeds  and  loosen  the 
soil.  Somewhat  higher  ridges,  usually  14  to  18  inches  above  the 
crowns,  are  then  made  by  the  use  of  18  or  20-inch  disks.  As  a  rule, 
the  field  must  be  gone  over  several  times  to  get  a  sufficiently  high 
ridge.  As  the  crowns  become  older,  they  grow  toward  the  surface 
and  spread  laterally,  making  necessary  the  use  of  more  soil  each  year. 
A  light  harrow,  chain,  or  wooden  float  is  often  attached  to  the  rear 
of  the  disk  to  break  the  clods  and  give  a  smooth  surface  to  the  ridge. 
The  space  between  the  ridges  is  also  disked  and  harrowed  thoroughly, 
as  it  often  becomes  badly  packed  by  the  cutters  during  the  green 
asparagus  season. 

Cutting. — During  harvesting  for  the  cannery,  the  entire  field  is 
cut  each  day.  All  the  spears  that  have  the  tips  through  the  ground 
or  that  are  breaking  the  ground  are  cut,  to  a  length  of  approximately 
9  inches,  with  a  chisel-shaped  knife. 

The  cutters  start  at  daylight  and  work  until  the  fields  have  been 
gone  over.  As  a  rule,  it  is  possible  to  can  each  day's  harvest  on  the 
same  day  it  is  cut.  The  cutters  lay  the  asparagus  on  top  of  the  ridges. 
The  spears  from  six  to  eight  rows  are  laid  on  the  two  center  ridges. 
Usually  only  one  row  is  cut  at  a  time,  as  fewer  of  the  spears  are  missed 
than  if  an  attempt  is  made  to  harvest  the  spears  from  two  rows.  If 
a  spear  is  missed,  it  will  be  green  by  the  following  day  and  will 
therefore  be  placed  in  the  green  pack.  Moreover,  it  has  been  found 
by  pedometer  tests  that  more  than  twice  as  many  steps  are  taken 
when  cutting  two  rows  as  when  cutting  one  row  at  a  time. 

White  asparagus  is  usually  gathered  and  hauled  from  the  field  in 
the  same  manner  as  green  asparagus.  From  the  fields  it  is  carted 
or  sleded  directly  to  the  washing  sheds,  which  are  located  along  the 
edges  of  the  fields. 

Trimming. — The  asparagus  is  taken  from  the  carts  or  sleds  and 
placed  in  wooden  forms  so  that  all  the  tips  touch  the  back.  When  the 
form  has  been  filled,  the  spears  are  held  firm  by  pressure  from  a* 
board  clamped  on  top.  They  are  then  trimmed  to  a  uniform  length 
of  about  7  inches  by  cutting  off  the  butts  with  a  long  knife.  A  large 
knife  made  from  a  cross-cut  saw  is  generally  used.  The  teeth  are  filed 


86  UNIVERSITY   OF    CALIFORNLi EXPERIMENT    STATION 

off  and  the  edge  is  usually  made  undulating  before  it  is  sharpened. 
A  few  growers  are  now  using  machines  for  both  trimming  and  wash- 
ing. When  a  machine  is  finally  perfected  these  operations  will  be 
greatly  facilitated,  at  least  on  the  larger  ranches. 

Washing. — After  trimming,  the  loose  dirt  is  washed  off  with  a 
stream  of  water  from  a  hose.  The  asparagus  is  then  taken  out  of  the 
form,  immersed  in  a  trough  of  water  and  washed  by  rubbing  the 
spears  together.  A  piece  of  rope  about  one  foot  long  with  a  loop  on 
each  end  is  usually  slipped  over  the  thumbs.  This  makes  it  possible 
for  the  worker  to  handle  much  larger  amounts  at  a  time.  It  requires 
skill  to  clean  the  spears  properly  during  the  washing  operation. 
Prompt  washing  after  harvesting  removes  the  adhering  soil  so  that 
it  will  not  stain  the  white  spears.  In  addition,  it  cools  the  spears  and 
retards  deterioration.  When  washed,  the  spears  are  placed  in  lug 
boxes  and  the  covers  nailed  on. 

Hauling  to  the  Cannery. — The  lugs  of  asparagus  are  collected 
from  the  washing  sheds  several  times  each  day  by  motor  trucks,  and 
are  hauled  directly  to  the  cannery  or  to  a  shipping  point.  Practically 
all  of  the  canneries  are  located  on  the  waterfront.  This  makes  it 
possible  to  haul  the  fresh  and  the  canned  products  by  boat. 

Grading. — The  asparagus  is  taken  from  the  lug  boxes  and  placed 
on  the  tables  in  front  of  the  sorters.  At  the  cannery,  experienced 
sorters,  usually  women,  grade  the  asparagus.  The  number  of  grades 
packed  varies  somewhat  among  the  different  canning  companies.  The 
white  and  green  spears  are  canned  in  practically  every  size  (fig.  35). 
At  the  present  time  the  demand  for  the  white  exceeds  that  for  the 
green.  The  green  asparagus  referred  to  in  canning  has  only  a  small 
amount  of  green  when  compared  with  that  shipped  fresh.  This  is 
usually  sold  as  "green  tips."  If  the  spears  have  loose  heads,  that  is, 
are  badly  "flowered,"  or  are  very  green,  they  are  cut  into  short 
lengths  for  soup  stock.  A  small  amount  of  peeled  spears  are  also 
canned.    Usually  only  the  very  large  spears  are  peeled. 

As  the  various  grades  are  sorted  out,  they  are  placed  in  small 
wooden  boxes  holding  about  three  pounds.  When  the  boxes  are  filled, 
they  are  carried  on  an  endless  conveyor  to  the  trimmers. 

Filling  the  Cans. — After  the  spears  have  been  trimmed,  they  are 
dumped  into  large  wicker  baskets.  These  are  then  immersed  in  vats 
of  water  at  or  near  the  boiling  point.  This  immersion  in  hot  water 
gives  the  spears  a  final  washing,  shrinks  them,  and  makes  them  more 
pliable.  When  brought  to  the  cannery,  the  spears  are  fresh  and 
brittle ;  immersion  in  hot  water  makes  it  possible  to  handle  them 
without  danger  of  breaking.    The  baskets  are  next  immersed  in  cold 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


87 


water,  or  the  spears  sprayed  with  cold  water.  The  asparagus  is  then 
placed  in  enamel-lined  sinks  filled  with  water.  A  final  sorting  for 
color  and  size,  and  an  inspection  for  blemishes  and  cleanliness  are 
made. 

The  cans  of  asparagus  are  filled  by  hand.  They  are  then  conveyed 
to  the  "briner"  and  filled  with  a  hot  salt  solution.  From  the  briner 
they  pass  through  an  exhaust  box,  where  the  air  is  drawn  from  the 
tissues  and  the  liquid.  The  cans  are  then  capped  by  an  automatic 
sealer. 


Fig.  35. — Grades  of  asparagus  for  canning:  1,  Giant;  2,  Colossal;  3,  Mam- 
moth; 4,  Large;  5,  Medium;  6,  Small;  7,  Tiny.  There  are  both  "shorts"  and 
"longs"  of  these  seven  grades. 

Square  containers  are  generally  used  for  asparagus.  The  vacuum 
produced  within  the  square  can,  after  cooling,  draws  in  the  four  sides 
and  holds  the  spears  so  that  they  cannot  move  about  and  rub  off 
the  side  leaves  and  buds.  In  the  round  can,  where  only  the  ends  are 
drawn  in,  there  is  more  freedom  of  movement  of  the  spears. 

Processing. — After  being  sealed,  the  cans  are  collected  in  iron 
trays,  loaded  on  trucks,  and  rolled  into  the  retorts,  which  are  equipped 
with  recording  thermometers.  Care  is  used  to  obtain  the  proper  heat- 
ing. After  processing  the  cans  are  stacked  in  a  cool,  well-ventilated 
room  before  being  placed  in  the  warehouse.  In  the  warehouse  the 
cans  are  tested  for  soundness  and  are  labelled  and  boxed.     Canned 


88  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

asparagus  seldom  moves  from  the  warehouse  for  several  weeks  after 
canning.  After  standing  for  a  time,  the  spears  within  a  can  become 
uniform  in  color  and  become  more  homogeneous  and  attractive. 

Quality. — Nearly  all  of  the  asparagus  is  canned  the  same  day  that 
it  is  cut.  The  canneries  begin  to  operate  about  the  middle  of  the  fore- 
noon, continuing  until  that  day's  harvest  has  been  canned.  The  great 
rapidity  of  deterioration  under  ordinary  storage  conditions  makes  it 
necessary  to  pack  soon  after  harvesting.  Bitting (2)  found  that  aspara- 
gus packed  3  or  4  hours  after  cutting  had  only  a  very  small  amount  of 
fibrous  material  at  the  butts  of  the  spears,  If  allowed  to  stand  24  hours 
before  packing  a  marked  increase  in  the  amount  of  fiber  in  the  "peel" 
and  at  the  butt  is  apparent.  If  there  is  a  holdover  from  the  previous 
day's  cutting,  it  is  the  custom  among  the  canners  to  use  only  the  tips 
of  the  spears. 

If  it  is  impossible  to  pack  the  same  day  the  spears  are  cut,  they 
should  be  stored  where  it  is  cool  and  moist.  At  ordinary  temperatures 
there  is  considerable  heating  of  asparagus  in  lug  boxes.  This  heating 
hastens  deterioration. 

Asparagus  Pack  of  California  and  Other  States. — Except  for  a 
few  years,  there  has  been  a  steady  increase  in  the  California  asparagus 
pack  since  the  industry  was  started  about  1890.  This  increase  will 
probably  continue  for  some  time  to  come  because  of  the  exploitation 
of  foreign  markets.  Canned  asparagus  has  also  been  looked  upon  as 
a  luxury  by  most  people.  It  is  rightly  the  aim  of  the  canners  to  make 
it  accessible  to  a  greater  portion  of  the  population  by  taking  it  out  of 
the  luxury  class. 

Exports  of  Canned  Asparagus.- — Before  the  development  of  the 
industry  in  California  nearly  all  of  the  canned  asparagus  used  in  the 
United  States  was  imported  from  France.  At  present  and  for  some 
years  past,  California  has  been  able  to  supply  the  entire  domestic 
demand  and,  besides,  has  shipped  canned  asparagus  to  almost  every 
country  and  province  in  the  world.  Export  data  obtainable  from  the 
Bureau  of  Commerce  Reports  give  the  destination  and  the  number  of 
pounds  shipped. 

In  1923,  8,766,431  pounds  of  canned  asparagus  were  exported  from 
the  United  States,  while  in  1924,  9,919,680  pounds  were  exported. 
The  imports  of  canned  asparagus  in  1922  and  1923  were  526  and 
6,787  pounds,  respectively. 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  89 


FUNGOUS    DISEASES 

Asparagus  Rust  (Puccinia  asparagi  D.C.). — Asparagus  rust  was 
first  discovered  in  America  in  1896.  The  same  year  the  disease  was 
reported  on  Long  Island,  in  Massachusetts,  and  in  Connecticut. 
Probably  the  rust  had  been  introduced  several  years  before  that  time 
and  had  spread  to  a  considerable  extent  before  being  observed.  The 
disease  spread  rapidly  throughout  the  entire  country,  and  within  a 
few  years  had  reached  the  Pacific  Coast.  In  California,  the  spread 
of  the  rust  was  from  south  to  north.  It  was  first  reported  in  southern 
California  and  in  the  Milpitas  district  near  San  Jose  in  1901 ;  on 
Bouldin  Island  and  the  surrounding  territory  as  far  up  the  Sacra- 
mento Valley  as  Grand  Island,  in  1902,  and  about  Vorden  and  the 
city  of  Sacramento,  in  1903. 

Injury  to  the  Host. — The  organism  does  not  injure  the  young 
shoots  that  are  cut  for  the  market  or  for  canning  purposes.  It  makes 
its  first  appearance  in  the  producing  fields  on  the  asparagus  stalks 
after  the  cutting  season  is  over.  As  is  well  known,  the  synthesis  of 
plant  foods  takes  place  in  the  green  tissue  of  the  asparagus  plant,  and 
these  foods  are  translocated  to  the  fleshy  roots  and  rhizome  and  there 
stored  in  large  quantity.  Pood  that  is  stored  in  the  crown  after  the 
commercial  crop  has  been  harvested  furnishes  energy  for  the  growth 
of  the  crop  the  following  season.  If  the  aerial  shoots  are  injured 
and  the  tissue  used  for  synthesis  of  food  is  reduced  in  amount  or  in 
effectiveness,  less  reserve  material  will  be  stored  in  the  crowns.  The 
succeeding  crop  will  be  reduced  in  proportion  as  the  reserve  food 
supply  is  diminished.  The  injury  caused  by  the  rust  organism  is  due 
mainly  to  destruction  of  the  tissues  that  carry  on  the  process  of 
food  synthesis.  When  the  rust  organism  attacks  a  plant,  little  or  no 
injury  is  appareunt  until  the  spore  clusters  rupture  the  epidermis. 
The  ruptured  areas  become  dry  and  take  on  a  brownish  color.  When 
the  attack  is  severe,  the  entire  plant  or  the  entire  field  becomes  brown 
and  dead  in  appearance. 

Life  History. — In  asparagus  rust  there  are  four  spore  forms,  as 
follows:  (1)  teleutospores,  (2)  sporidia,  (3)  aecidiospores,  and  (4) 
uredospores.  All  of  these  occur  on  the  asparagus  plant.  They  arise 
from  a  mycelium  which  penetrates  the  tissues  of  the  host.  The  rust 
winters  over  in  the  soil  or  on  the  old  asparagus  plants  in  the  resting 
or  teleutospore  stage.  These  resting  spores  are  two-celled  (fig.  36). 
They  germinate  in  the  spring  of  the  year  at  about  the  same  time  that 


90 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  36. — A  cluster  of  teleutospores  (winter  spores)  breaking 
through  the  epidermis.     (From  Bui.  165.) 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


91 


the  asparagus  plant  starts  to  grow.  From  each  cell  of  these  thick- 
walled  spores  there  normally  arises  a  short  segmented  filament  or 
promycelium  bearing  four  small  sporidia.  These  sporidia  are  carried 
by  wind,  water  or  other  means  into  contact  with  young  shoots.  Here, 
in  the  presence  of  moisture,  they  germinate  upon  the  surface  of  the 
plant,  and  the  mycelium  grows  through  the  epidermis  and  establishes 
itself  in  the  underlying  tissue.    This  mycelium,  after  a  growing  period 


Fig.  37. — Left,  three  separate  germinating  uredospores.  The  other  figure 
shows  a  uredospore  germinating  on  the  surface  of  the  plant  and  entering  the 
stoma.     (From  Bull.  165.) 


of  less  than  a  month,  varying  with  climatic  conditions,  starts  to 
produce  spores.  These  spores  appear  grouped  under  the  epidermis, 
each  aggregation  being  known  as  a  cluster  cup  or  aecidium.  The 
aecidia  appear  in  rather  long,  light  green  areas.  The  aecidiospores 
are  one-celled  and  orange  colored.  The  developing  spores  of  the 
aecidium  finally  rupture  the  epidermis  and  are  liberated.  The  aecidio- 
spores are  produced  in  series  or  chains.  The  outside  cells  of  the  chains 
become  rounded,  are  cut  off,  and  are  finally  set  free. 


92 


UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 


The  aecidiospores  are  carried  mainly  by  the  wind  and  may  fall 
upon  the  stems  and  cladophylls  of  the  same  or  other  asparagus  plants. 
In  the  presence  of  moisture,  these  spores  germinate  and  produce  a 
mycelium  that  grows  through  the  stomata  opening  into  the  chloro- 
phyll-bearing tissue  below  (figs.  37  and  38).  The  fungal  threads  are 
localized  mainly  in  the  chlorophyll-bearing  tissue,  and  in  their  growth 
force  the  cells  of  the  host  apart.     Food  is  absorbed  from  the  cells  of 


Fig.  38. — Uredospore  germinating  on  the  surface  of  the  plant,  and  penetrating 
the  stoma.     Portion  of  asparagus  stem  shown  in  cross-section.     (From  Bui.  165.) 

the  host  plant,  for  the  nourishment  of  the  parasite,  by  the  special 
absorptive  organs  known  as  haustoria.  This  mycelium  produces  the 
summer  rust,  red  rust,  or  uredospore  stage,  which  is  the  one  in  which 
the  greatest  amount  of  damage  is  done.  The  first  signs  of  the  summer 
rust  appears  two  or  three  weeks  after  infection  by  the  aecidiospores. 
The  clusters  of  developing,  single-celled  uredospores  rupture  the 
epidermis  (fig.  39),  and  the  spores  are  carried  by  air  currents,  gravity 
or  other  means  to  reinfect  other  plants  or  different  portions  of  the 
same  plant.  At  this  stage,  especially  in  regions  of  excessive  summer 
rainfall  or  where  summer  dews  are  prevalent,  the  spread  of  the  rust  is 
very  rapid.  Under  favorable  conditions  of  temperature  and  moisture, 
the  life  cycle  from  uredospore  to  uredospore  is  reported  as  often  being 
less  than  twelve  days.    These  spores  are  the  chief  means  of  distribut- 


Bul.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


93 


ing  the  disease  during  the  growing  season.  According  to  Smith  the 
uredospores  when  dry  retain  their  viability  for  a  period  of  three  or 
four  months. 


Fig.  39. — A  cluster  of  uredospores  (summer  spores)  breaking  through  the 
epidermis  of  the  host.  Note  the  fungus  threads  in  the  tissue  of  the  host. 
(From  Bul.  165.) 

Accompanying  the  uredospore  stage  and  sometimes  occurring 
alone,  is  the  teleutospore  stage,  also  known  as  the  fall  or  winter  rust 
stage.  The  teleutospores  appear  in  greatest  abundance  in  the  late 
summer  and  early  fall  and  arise  from  the  same  mycelium  as  the 
uredospores.    Most  of  the  teleutospores  adhere  to  the  plant  and  prob- 


94  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

ably  provide  the  only  means  of  carrying  the  disease  over  winter.  They 
remain  dormant  until  temperature  and  moisture  conditions  are  favor- 
able for  their  development  the  following  spring.  The  teleutospores 
probably  lose  their  viability  after  about  one  year.  Smith (21)  (Cali- 
fornia) collected  teleutospores  from  the  previous  year's  crop  on 
June  27  and  in  a  number  of  tests  was  able  to  get  only  one  spore  to 
germinate.  Either  the  spores  had  lost  their  viability  or  they  had 
germinated  previously. 

Environmental  Relations. — The  prevalence  of  asparagus  rust  is 
closely  related  to  environmental  conditions.  Moisture  is  necessary  for 
the  germination  of  the  spores.  In  the  east,  where  dews  are  prevalent 
throughout  the  entire  growing  season,  the  spread  of  the  rust  from  plant 
to  plant  and  from  field  to  field  is  very  rapid.  In  the  dry,  semi-arid 
regions  of  the  west,  the  asparagus  rust  does  not  spread  so  rapidly. 
Smith(22)  states  "that  the  amount  of  rust  varies  directly  and  exactly 
with  the  amount  of  dew,  and  that  so  long  as  there  is  little  or  no  dew 
there  can  be  no  rust."  The  Imperial  Valley  of  California  is  notably 
free  from  dew  and  also  free  from  asparagus  rust.  In  the  San  Fer- 
nando Valley,  where  dews  are  frequent,  the  rust  does  considerable 
damage.  Also,  in  that  part  of  the  Santa  Clara  Valley  adjacent  to  the 
lower  end  of  San  Francisco  Bay,  summer  dews  are  prevalent,  and  the 
asparagus  fields  are  subject  to  severe  epidemics  of  rust.  This  region 
is  now  a  much  less  important  asparagus  producing  center  than  it  was 
two  decades  ago.  In  the  Delta  there  is  very  little  or  no  summer  rain, 
dew,  or  fog,  and  rust  is  of  minor  importance  during  most  years, 
except  on  the  young  beds  which  are  harvested  for  only  a  short  time. 
The  prevailing  winds  on  the  California  coast  are  from  the  west,  but 
in  the  great  interior  valley  the  general  direction  of  the  winds  is 
changed  to  "up  valley."  A  strong  westerly  breeze  usually  blows 
inland  through  the  Straits  of  Carquinez,  which  is  the  outlet  of  both 
valleys.  The  "summer  trade  winds"  set  in  regularly  some  time  in 
May  and  continue  with  but  an  occasional  interruption  by  a  "  norther ' ' 
until  October.  This  strong  westerly  wind  blows  over  the  Delta 
throughout  the  summer  and  prevents  the  deposition  of  dew  except 
behind  windbreaks  or  in  other  wind  protected  situations.  It  is  in  these 
sheltered  places  that  rust  usually  makes  its  first  appearance. 

Resistant  Varieties, — Martha  Washington  is  claimed  to  be  the  most 
highly  rust-resistant  variety  of  asparagus  grown  in  America  today. 
While  Mary  Washington  may  be  slightly  less  resistant  to  rust  attack 
than  the  Martha  Washington,  it  does  not  suffer  appreciably  from  rust 
attack.     Mary  Washington  seems  to  be  somewhat  more  susceptible,. to 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  95 

attack  of  rust  in  California  than  in  the  eastern  states.  These  two 
varieties,  however,  have  almost  replaced  all  other  varieties  where  rust 
is  prevalent.  Mary  Washington  is  becoming  very  popular  in  nearly 
all  of  the  important  asparagus  growing  regions,  not  only  because  of  its 
rust  resistance  but  because  of  its  earliness,  large  size,  and  tendency 
for  the  growing  spears  to  hold  a  tight  head  longer  than  other  varieties. 

Spraying  and  Dusting. — In  the  eastern  states  much  experimental 
work  was  done  to  determine  the  best  methods  of  dusting  and  spraying 
but  the  results  were  never  entirely  satisfactory.  Smith, VZI>  working 
in  California,  found  that  dusting  with  sulfur  gave  satisfactory  control. 
When  rust  appears  early,  one  application  of  25  to  30  pounds  to  the 
acre  about  three  weeks  after  the  cutting  season,  and  another  about  a 
month  later,  should  usually  be  sufficient.  On  newly  planted  beds  or 
when  cutting  stops  early  in  the  season,  more  than  two  applications 
may  be  necessary.  However,  it  is  impossible  to  give  specific  directions 
that  will  cover  all  conditions.  Finely  divided  sulfur  gives  the  best 
results.    The  plants  should  be  thoroughly  covered  with  dust. 

If  the  acreage  is  small,  the  sulfur  can  be  applied  with  a  hand 
duster;  in  large  fields,  however,  a  power  duster  should  be  used  that 
will  cover  several  rows  at  a  time. 

Other  Methods  of  Control. — Burning  the  stalks  of  infested  fields 
in  the  fall  will  kill  many  of  the  spores.  This  does  not  add  greatly  to 
the  preventive  methods,  however,  as  the  "needles"  which  have  become 
infected  fall  off  after  severe  frosts  and  usually  before  the  tops  are 
cut  and  burned.  Volunteer  plants  about  the  edges  of  the  fields,  in 
fence  rows,  and  on  the  levees  and  ditch  banks,  should  be  grubbed  out 
so  that  they  will  not  harbor  the  disease. 

The  fields  should  be  planted  so  that  they  will  secure  good  aeration ; 
the  rows  should  run  in  the  direction  of  the  prevailing  winds.  It  is 
usually  inadvisable  to  plant  windbreaks  about  the  asparagus  fields. 
In  regions,  such  as  the  Delta,  where  rust  usually  does  not  appear  on 
the  older  beds  until  fall,  the  best  and  cheapest  method  of  rust  control 
is  to  secure  good  field  aeration. 

Violet  Root  Rot  (Rhizoctonia  crocorum  var.  asparagi  (Pers.) 
D.C.). — In  parts  of  Europe  the  losses  from  violet  root  rot  of  asparagus 
have  been  widespread  and  sometimes  severe.  The  disease  has  been 
reported  in  the  United  States,  but  has  occasioned  no  losses  worthy  of 
note. 

In  the  asparagus  bed,  violet  root  rot  is  usually  first  noticed  attack- 
ing only  a  few  plants,  but  every  year,  unless  the  disease  is  checked, 
new  surrounding  plants  are  infected  and  die.     On  newly  infected 


96  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

plants,  the  mycelium  shows  itself  on  the  roots  as  a  violet-colored  mass 
of  filaments.  In  badly  infected  plants,  the  soft  tissue  of  the  roots  is 
largely  destroyed,  and  they  have  the  appearance  of  hollow,  withered 
tubes,  sometimes  covered  with  characteristic  small  violet  or  dark  tufts. 


INSECTS   AND   OTHER    PESTS 

The  asparagus  plant,  both  in  Europe  and  America,  is  host  to  a 
number  of  very  destructive  insect  pests. 

The  Common  Asparagus  Beetle  (Crioceris  asparagi  L.). — The 
common  asparagus  beetle  is  found  in  almost  all  of  the  asparagus 
growing  regions  of  Europe  and  America.  In  the  United  States  the 
damage  caused  by  it  appears  to  be  less  in  the  southern  than  in  the 
northern  states.  So  far  as  known,  it  has  not  been  reported  as  occur- 
ring in  the  Imperial  Valley  of  California. 

Description. — The  adult  beetle  is  a  slender  and  graceful  insect, 
slightly  less  than  one-fourth  inch  long.  It  is  blue-black  in  color  with 
red  thorax  and  dark  blue  wing  covers,  marked  with  lemon  yellow  and 
with  reddish  borders.  The  markings  of  the  wing  covers  are  quite 
variable,  the  pale  color  sometimes  forming  submarginal  spots,  while 
in  other  specimens  it  becomes  so  diffused  as  to  form  the  principal  color 
of  the  wing  covers.  Like  a  squirrel,  it  commonly  hides  on  the  opposite 
side  of  the  branch  when  approached.  The  egg  is  dark  brown  and 
oval,  is  nearly  one-sixteenth  of  an  inch  long,  and  is  laid  on  end.  The 
eggs  are  deposited  upon  the  stems  or  foliage,  usually  two  to  seven  or 
more  in  a  row.  The  mature  larva  is  about  one-third  of  an  inch  long, 
soft  and  fleshy,  much  wrinkled,  and  of  a  dark  gray  or  olive  color,  with 
shining  black  head  and  legs.  The  mature  larva  drops  to  the  ground 
from  the  asparagus  plant,  and  just  beneath  the  soil  surface  forms  a 
small,  rounded,  thin,  earth-covered  cocoon  (fig.  40),  within  which  it 
changes  to  the  pupa,     The  latter  is  yellowish  in  color. 

Life  History. — The  insect  winters  over  in  the  adult  stage,  hiber- 
nating in  rubbish  and  other  protected  places.  In  the  latitude  of  the 
District  of  Columbia  (Chittenden),  the  beetles  usually  appear  in 
April,  but  as  a  rule  in  most  districts  they  appear  about  the  same  time 
as  the  asparagus  in  the  spring.  The  beetles  soon  start  to  lay  eggs. 
These  hatch  in  from  three  to  eight  days,  depending  on  the  tempera- 
ture. The  larvae  soon  become  full  grown  in  from  ten  to  fourteen 
days,  and  then  pupate  in  the  soil.  The  adult  beetle  emerges  in  about 
a  week.  The  insect  may  pass  through  its  entire  life  cycle  in  as  short  a 
time  as  three  weeks,  though  it  may  take  a  month  or  more.     In  its 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


97 


Fig.  40. — Cocoons  of  asparagus  beetle.    Observe  the  adult  beetle. 


98  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

northern  range,  usually  two  generations  are  produced  in  a  season ; 
farther  south,  as  many  as  four  broods  may  be  produced.  In  California 
(Essig(9))  there  are  many  overlapping  generations  each  year. 

Nature  of  Injury. — Both  the  larval  and  adult  stages  of  the  aspara- 
gus beetle  feed  upon  the  marketable  spears  as  well  as  upon  the 
foliage  and  stems  of  the  mature  stalks.  During  the  cutting  season  the 
adults  do  the  greatest  amount  of  damage  by  depositing  their  eggs 
upon  and  eating  holes  in  the  spears,  making  them  unsightly  and 
lowering  their  market  value. 

Control. — Asparagus  beetles  are  held  in  check  to  a  certain  extent 
by  natural  enemies.  Several  species  of  ladybird  beetles  feed  upon  the 
eggs,  while  numerous  soldier-bugs  and  small  dragon  flies  prey  upon 
the  larvae.  According  to  Johnston (13)  at  times  the  beetle  is  kept  under 
control  by  a  parasitic  wasp-like  fly,  Tetrastichus  asparagi  Cwfd.  The 
parasite  deposits  its  eggs  on  those  of  the  asparagus  beetle ;  the  beetle 
egg  hatches,  the  larva  grows  to  maturity,  enters  the  soil  and  forms  a 
pupal  cell  but  does  not  pupate  because  the  pupa  is  entirely  consumed 
by  the  parasite.  The  parasites  pupate  and  later  come  forth  as  adults 
from  the  cell  which  the  beetle  larva  has  constructed. 

In  the  Concord,  Massachusetts,  district  Chittenden(6)  has  observed 
that  large  numbers  of  hibernating  beetles  are  killed  during  the  winter, 
especially  when  extremely  low  temperatures  follow  a  period  of  warm 
weather.  During  extremely  high  temperatures,  exposed  larvae,  as 
well  as  eggs,  are  destroyed.  This  injury  by  extremes  of  temperature 
probably  holds  this  pest  in  check  in  the  far  northern  and  the  extreme 
southern  districts  and  probably  accounts  for  its  not  being  found  in 
the  Imperial  Valley. 

Chickens  and  ducks  feed  upon  both  the  adults  and  the  larvae  and 
do  not  injure  the  plants;  however,  their  use  is  limited  to  small  areas. 

Air-slacked  lime  dusted  on  the  plants,  when  wet  with  dew,  will  kill 
the  larvae  but  not  the  adults. 

In  certain  districts  where  the  attacks  are  especially  severe,  the 
spears  are  cut  white;  as  soon  as  the  tips  appear,  they  are  harvested 
before  the  beetle  has  an  opportunity  to  do  any  great  amount  of 
damage.  When  cutting  white  asparagus,  trap  hills  or  trap  rows  of 
asparagus  can  be  used  to  good  advantage.  The  beetles  are  forced  to 
congregate  and  feed  on  the  rows  or  hills  that  are  not  being  cut.  These 
should  be  thoroughly  dusted  or  sprayed  with  an  arsenical  every  week 
or  ten  days.  It  will  also  be  necessary  to  grub  out  the  volunteer  host 
plants  about  the  edges  of  the  fields  and  ditches  if  good  results  are  to 
be  expected. 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  99 

Where  green  asparagus  is  being  cut,  trap  crops  are  not  so  effective, 
as  the  beetles  can  feed  and  lay  their  eggs  upon  the  young  spears  before 
they  are  harvested.  The  spears  are  cut,  however,  before  the  eggs 
hatch.  On  the  young  beds,  and  after  the  cutting  season  on  the  older 
ones,  an  excellent  method  of  control  is  to  spray  with  lead  arsenate, 
using  4  pounds  of  lead  arsenate  paste  and  4  pounds  of  resin  fishoil 
soap  to  50  gallons  of  water.  A  dust  comprised  of  1  part  of  powdered 
arsenate  and  8  to  10  parts  of  air-slaked  lime  applied  while  the  plants 
are  wet  with  dew  will  also  give  excellent  control.  Young  larvae  are 
effectively  killed  with  5  per  cent  nicodust. 

A  number  of  asparagus  growers  in  the  Delta  report  complete 
extermination  of  hibernating  beetles  in  fields  that  have  been  flooded 
during  the  winter. 

To  obtain  the  best  control,  community  action  is  necessary. 

The  Twelve-spotted  Asparagus  Beetle  (Crioceris  duodecimpunc- 
tata  L.)  has  not  been  reported  as  occurring  in  the  western  United 
States  and  is  probably  confined  to  the  eastern  half. 

Asparagus  Miner  (Agromyza  simplex  Loew.). — The  asparagus 
miner  has  a  wide  distribution  and  has  been  reported  as  occurring  in 
many  sections  of  the  country,  including  Florida,  Texas,  Washington, 
and  California.    At  times  it  becomes  very  abundant  in  the  north. 

Description. — According  to  Fink(14)  the  adult  is  a  glistening 
metallic  black  fly  about  one-sixth  of  an  inch  in  length  and  with  a  wing 
expanse  of  about  one-fifth  of  an  inch.  The  males  are  somewhat  smaller 
than  the  females,  and  have  a  more  or  less  triangular  shaped  abdomen. 
One  of  the  striking  features  in  the  adult  is  a  picture  of  a  face  on  the 
thorax.  When  first  laid,  the  egg  is  glistening  white  in  color.  It 
measures  0.5  millimeters  in  length  and  0.12  millimeters  in  width.  The 
egg  is  elongate-oval,  slightly  widened  at  one  end,  and  more  or  less 
pointed  at  the  other.  The  egg  shell  is  at  first  viscid  and  transparent 
so  that  the  embryo  is  clearly  visible  through  the  shell.  When  first 
hatched,  the  larva  is  pure  white,  but  when  fully  grown  is  cream-Avhite. 
When  mature  it  is  4-5  millimeters  long,  about  five  times  longer  than 
wide,  of  nearly  uniform  diameter  throughout  a  greater  portion  of  its 
length,  and  narrowing  slightly  toward  either  end.  When  first  formed, 
the  pupa  is  light  brown ;  later  it  becomes  dark  brown.  It  is  flat  and 
curved  when  viewed  from  the  side.  A  pair  of  hooks  is  borne  at  each 
end  of  the  pupa,  by  means  of  which  it  attaches  itself  firmly  beneath 
the  epidermis  of  the  asparagus  stalk. 

Life  History. — Fink(10)  reports  that  in  the  vicinity  of  Ithaca,  New 
York,  the  adults  probably  make  their  appearance  about  the  middle  of 


100  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

May,  the  males  appearing  several  days  before  the  females.  The  female 
starts  to  deposit  eggs  within  a  week  after  she  emerges.  Eggs  are 
usually  laid  at  the  base  of  the  stalk,  at  or  near  the  surface  of  the 
ground  or  below  the  surface,  if  the  soil  is  loose.  The  eggs  are  deposited 
individually  just  below  the  epidermis.  It  is  rather  difficult  to  find 
the  eggs  unless  the  female  is  found  ovipositing.  If  a  stalk  on  which 
the  oviposition  has  been  observed  is  pulled  out  and  examined  carefully 
with  a  hand  lens,  tiny  punctures  leading  to  raised  areas  will  be^seen. 
If  the  epidermis  is  carefully  peeled  from  these  raised  areas,  the  egg 
is  found  adhering  either  to  the  peeled  epidermis  or  to  the  tissues  of 
the  stalk  below.  It  is  more  difficult  for  the  female  to  penetrate  old 
stalks,  and  in  case  eggs  are  deposited  on  these  part  of  the  egg  may 
remain  protruding  from  the  epidermis. 

The  entire  life  cycle,  except  the  adult  stage,  is  passed  in  conceal- 
ment beneath  the  epidermis  of  the  asparagus  stalk. 

The  eggs  hatch  in  twelve  to  eighteen  days.  When  hatched  the 
larvae  begin  to  mine  their  way  up  the  stalk  for  a  foot  or  more  above 
the  surface  of  the  soil  and  then  work  downward  again,  thus  producing 
zigzag  mines.  Usually  a  number  of  larvae  are  found  on  the  same 
stalk.  When  nearly  full-grown,  the  larvae  direct  their  mines  down- 
ward. During  the  summer  they  may  pupate  anywhere  along  the 
stalk;  later  they  pupate  at  depths  of  one  inch  or  more  below  the  soil 
surface.  The  pupae  are  found  in  the  mines  where  larvae  have  stopped 
feeding.  During  the  summer,  the  insects  remain  in  the  pupal  stage 
two  to  three  weeks.  The  fall  brood,  however,  winters  over  in  the 
pupal  stage. 

In  California,  according  to  Essig,(9)  the  flies  appear  early  in  the 
spring ;  there  are  at  least  two  generations  a  year. 

Nature  of  Injury. — The  injury  to  the  asparagus  stalks  is  done  by 
the  larvae  which  mine  at  the  base  of  the  stalk  under  the  epidermis. 
Chittenden (6)  reports  finding  pupae  under  the  outer  skin  of  the  roots, 
also.  Cases  have  been  reported  in  which  entire  beds  have  been 
destroyed  by  the  ravages  of  this  insect.  The  adult  does  not  lay  eggs 
on  the  young  spears  (Fink)  during  the  cutting  season,  but  by  prefer- 
ence oviposits  on  the  stalks  in  the  new  beds  and  in  the  nursery. 

Control. — Methods  of  control  used  at  the  present  time  are  not 
entirely  satisfactroy.  Fink(10)  recommends  the  addition  of  syrup  as 
an  attractant  to  an  arsenical  spray,  which  is  used  to  kill  the  adults. 
He  also  recommends  pulling  and  destroying  the  infested  stalks  in  late 
fall  or  early  spring.  These  stalks  generally  turn  yellow  and  in  severe 
cases  die  before  the  non-infested. 


Btjl.  446] 


THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA 


101 


The  Asparagus  Fly  (Platyparea  pocciloptera  Schrank). — So  far 
no  mention  has  been  made  of  this  pest  in  the  United  States. 

The  Garden  Centipede  (Scutigerella  immacidata  Newport). — The 
garden  centipede  is  found  widely  distributed  throughout  the  world. 
It  is  an  economic  pest  in  many  of  the  important  truck  crop  regions 
of  California,  Oregon,  and  Utah.  So  far  as  known,  it  has  not  been 
reported  as  a  serious  asparagus  pest  except  in  the  Delta  region  of 
California. 


Fig.  41. — Asparagus  or  garden 
centipede  (adult).    X  10. 


Fig.  42. — Eggs  of  the  garden 
centipede  (much  enlarged). 


Description. — The  adult  (fig.  41)  is  small  and  unusually  white  in 
color,  though  its  body  is  often  tinged  by  colored  food  material  in  the 
digestive  tract.  When  feeding  on  young  asparagus  shoots,  however, 
they  are  almost  transparent  white.  According  to  Wymore,(28)  the 
adults  vary  in  length  from  2.7  to  6.7  millimeters;  they  have  one  pair 
of  many-jointed  antennae,  an  eye-like  body  just  back  of  each  antenna, 
four  pairs  of  mouth  appendages;  twelve  pairs  of  well-developed  legs, 
the  first  pair  four-jointed,  all  the  rest  five-jointed. 

Life  History. — According  to  Wymore,(28)  "When  first  laid  the 
eggs  are  a  pearly  white  and  as  the  time  for  hatching  approaches  they 
become  a  dirty  white  color  (fig.  42).  They  are  %  to  %  millimeter  in 
diameter  and  are  covered  with  tiny  ridges  giving  the  appearance  of  a 
net  work. 

"When  just  hatched  the  larvae  are  hairy,  vary  from  0.9  to  1.1 
millimeters  in  length,  and  have  six  pairs  of  legs."  The  first  molt 
occurs  three  to  five  days  after  hatching. 


102  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  43. — Injury  to  asparagus  due  to  garden  centipede. 


BuL.  446]  TPIE   ASPARAGUS   INDUSTRY   IN    CALIFORNIA  103 

The  life  history  has  not  been  worked  out  in  detail.  Wymore  was 
able  to  find  adult  specimens  in  the  soil  about  the  asparagus  crowns  at 
almost  any  time  of  the  year.  During  the  first  part  of  June,  the  young 
greatly  outnumber  the  adults,  but  by  the  middle  of  August,  90  per 
cent  of  the  individuals  taken  in  the  field  were  mature. 

The  centipedes  feed  beneath  the  surface  of  the  soil,  eating  small 
holes  in  the  spears  and  making  them  unfit  for  canning. 

Control. — Wymore (28)  recommends  flooding  for  a  period  of  two 
weeks  where  the  ground  is  kept  covered  to  a  depth  of  a  foot  or  more 
and  all  asparagus  tops,  stubble,  and  other  debris  are  entirely  sub- 
merged. He  states  that  where  the  soil,  but  not  the  stubble,  was  covered 
with  four  or  five  inches  of  water,  very  good  results  were  obtained  by 
stirring  up  the  muddy  soil  with  a  potato  hook,  thus  disturbing  the 
centipedes  and  allowing  water  to  reach  them  more  quickly.  If  this 
was  not  done,  it  seemed  impossible  to  drown  the  pests,  although  the 
soil  was  kept  covered  for  three  or  four  weeks  with  several  inches  of 
water.  Evidently  in  this  case,  the  insects  found  lodgment  in  and 
about  the  stems  and  received  sufficient  oxygen  which  was  conveyed 
down  the  stems  that  projected  above  the  water  surface.  Flooding  as 
a  means  of  control  cannot  be  used  in  many  of  the  asparagus  districts 
outside  of  the  Delta,  except  where  a  large  supply  of  water  is  available. 
To  date,  satisfactory  control  methods  by  use  of  repellants  and  soil- 
fumigants  have  not  been  developed. 

Other  Pests. — Other  insects  reported  by  Essig  as  feeding  on 
asparagus  in  California  are :  the  Harlequin  Cabbage  Bug  {Murgentia 
histrionica  Hahn.),  Orange  Tortrix  (Tortrix  citrana  Fernald),  and 
the  Yellow  Bear  Caterpillar  (Diacrisea  virginica  Fab.).  Wymore 
observed  that  the  tops  of  several  acres  of  asparagus  in  the  Delta  in 
the  late  autumn  of  1922  turned  white  from  the  injury  of  pentotomids 
(chiefly  Chlorochrou  sayi  Stal.  and  Thyanta  eitstator  Fab.).  The  bugs 
were  found  in  large  clusters  on  the  stems  about  18  inches  from  the 
tips  of  the  branches,  where  they  were  girdled  by  the  many  punctures 
from  the  mouth  parts. 

The  authors  have  observed  red  spider  and  thrips  in  considerable 
abundance  on  the  asparagus  plants,  especially  during  late  summer. 
Thrips  injury  has  been  found  to  be  very  serious  in  nursery  beds  in 
the  San  Fernando  Valley.  In  early  spring  Aphis  sp.  are  often  found 
on  the  spears  and  on  the  young  seedlings  in  the  nursery.  Gophers 
feed  upon  both  the  fleshy  roots  and  stalks  and  do  considerable  damage 
if  not  trapped. 


104  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


LITERATURE    CITED 

i  Bisson,  C.  S.,  H.  A.  Jones,  and  W.  W.  Bobbins. 

1926.     Factors  influencing  the  quality  of  fresh  asparagus  after  it  is  har- 
vested.    California  Agr.  Exp.  Sta.  Bui.  410:1-28. 

2  Bitting,  K.  G. 

1917.     Deterioration  in  asparagus.     Nat.  Canners  Assoc.  Bui.  11:1-18. 
s  Borthwick,  H.  A. 

1925.     Factors  influencing  the  rate  of  germination  of  the  seed  of  Asparagus 
officinalis.     California  Agr.  Exp.  Sta.  Tech.  Paper  18:1-17. 
*  Bottner,  J. 

1921.     Praktischer    Lehrbuch    des    Spargelbaues    122:     p.    74,    figs.    1-74. 
Trovitsch,  Frankfurt. 

5  Brooks,  W.  P.,  and  F.  W.  Morse. 

1919.     A  fertilizer  experiment  with  asparagus.      Massachusetts  Agr.   Exp. 
Sta,  Bui.  194:231-257. 

6  Chittenden,  F.  H. 

1917.     The  asparagus  beetles  and  their  control.    U.  S.  Dept,  Agr.  Farmers' 
Bui.  837:1-13. 
<  Close,  C.  P. 

1903.     Report    of   the    horticulturist.      I.    Nitrate    of    soda    on    asparagus. 
Delaware  Agr.  Exp.  Sta.  Ann.  Kept.  14:89-90. 
s  Close,  C.  P.,  T.  H.  White,  and  W.  R.  Ballard. 

1911.     Fertilizers  on  asparagus.     Maryland  Agr.  Exp.  Sta.  Bui.  151:135- 
146. 
9  Essig,  E.  O. 

1915.     Injurious  and  beneficial  insects   of   California,      (Ed.    2.)      Monthly 
Bui.  California  State  Comm.  Hort.  Supplement,  pp.  1-541. 
io  Fink,  D.  E. 

1913.     The    asparagus    miner    and    the    twelve-spotted    asparagus    beetle. 
Cornell  Agr.  Exp.  Sta,  Bui.  331:411-435. 
ii  Greene,  W.  J. 

1891.     Asparagus.     Ohio  Agr.  Exp.  Sta,  Bui.  24   (2nd  ser.  2):241-244. 
12  Ilott,  Chas. 

1901.     The  book  of  asparagus.     108  pp.    John  Lane,  London  and  New  York, 
is  Johnston,  Frederick  Andrew 

1915.     Asparagus-beetle  egg  parasite.     Jour.  Agr.  Res.  4:303-314. 
i^Loisel,  M. 

1924     L'Asperge,  culture  naturelle  et  artificielle.     Librairie  Agricole  de  la 
Maison  Rustique.     (10th  ed.)  136  pp.     F.  Lesourd,  Paris, 
is  Meyer,  E.  H. 

1913.     Spargelbau   und   Konservegemiise   nach   Braunschweiger   Methode. 
(ed.  2.)  63  pp.    Paul  Parey,  Berlin, 
ic  Morse,  Fred  W. 

1913.     Some    effects    of    fertilizers    on    the    growth    and    composition    of 
asparagus  roots.    Massachusetts  Agr.  Exp.  Sta.  Ann.  Rept.  25:156. 


BUL.  446]  THE   ASPARAGUS    INDUSTRY    IN    CALIFORNIA  105 

17  Myers,  C.  E. 

1916.  Experiments  with  asparagus.  Pennsylvania  State  College  Ann.  Rept., 
pp.  557-578. 

is  Norton,  J.  B. 

1919.     Washington  asparagus:  information  and  suggestions  for  growers  of 
new    pedigreed    rust-resistant    strains.      U.  S.    Dept.    Agr.    Off. 
Cotton,  Truck  and  Forage  Diseases  Circ.  7:1-8. 
is  Rousseaux,  E.,  and  C.  Brioux.  x 

1906.  Recherches  sur  la  culture  de  l'Asperge  dans  l'Auxerrois.    (Memoirs 

Societe    d 'encouragement    pour    l'industrie    nationale)     112    pp. 
Siege  de  la  Societe,  Paris. 
20  Rudolfs,  W. 

1921.  Experiments  with  common  rock  salt.     I.  Effect  on  asparagus.     Soil 

Sci.  12:449-456. 
2i  Smith,  R.  E. 

1905.  Asparagus  and  asparagus  rust  in  California.  California  Agr.  Exp. 
Sta.  Bui.  165:1-99. 

22  Smith,  R.  E. 

1904.  Report  on  asparagus  rust  investigations.     California  Agr.  Exp.  Sta. 

Circ.  9:1-20. 

23  Tiedjens,  Victor  A. 

1924.  Some  physiological  aspects  of  Asparagus  officinalis.  Proc.  Amer. 
Soc.  Hort.  Sci.  21:129-140. 

24  Walker,  E. 

1905.  Asparagus  and  salt.     Arkansas  Agr.  Exp.  Sta.  Bui.  86:31-36. 

25  Warren,  G.  F.,  and  Jennie  A.  Voorhees. 

1907.  JSTew  Jersey  Agr.  Exp.  Sta.  Ann.  Rept.  27:189-223. 

26  Working,  E.  B. 

1922.  Physical  and  chemical  factors  in  the  growth  of  asparagus.     Carnegie 

Inst.  Wash.  Year  Book  21:63-64. 

27  Working,  E.  B. 

1924.  Physical  and  chemical  factors  in  the  growth  of  asparagus.  Arizona 
Agr.  Exp.  Sta.  Tech.  Bui.  5:85-124. 

28  Wymore,  F.  H. 

1924.  The  garden  centipede,  Scutigerella  immaculata  (Newport),  a  pest 
of  economic  importance  in  the  West.  Jour.  Econ.  Ent.  17:520- 
526. 


STATION  PUBLICATIONS   AVAILABLE   FOR  FREE   DISTRIBUTION 


No. 

253.  Irrigation  and  Soil  Conditions  in  the 
Sierra   Nevada   Foothills,    California. 

262.  Citrus   Diseases   of   Florida   and   Cuba 

Compared  with   those  of  California. 

263.  Size  Grades  for  Ripe  Olives. 

268.   Growing  and  Grafting  Olive  Seedlings. 

273.  Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain,  Fresno 
County,   California. 

276.  The  Pomegranate. 

277.  Sudan   Grass. 

278.  Grain    Sorghums. 

279.  Irrigation   of   Rice  in   California. 
283.  The  Olive  Insects  of  California. 
294.   Bean   Culture  in   California. 

804.  A   Study  of  the  Effects  of  Freezes  on 

Citrus    in    California. 
310.  Plum    Pollination. 
312.  Mariout   Barley. 
813.   Pruning      Young      Deciduous       Fruit 

Trees. 
819.   Caprifigs    and    Capriication. 
324.   Storage  of   Perishable  Fruit  at   Freez 

ing  Temperatures. 
825.   Rice     Irrigation     Measurements     and 

Experiments    in    Sacramento    Valley, 

1914-1919. 
328.   Prune   Growing   in    California. 
331.   Phylloxera-Resistant    Stocks. 
835.   Cocoanut    Meal    as    a    Feed    for    Dairy 

Cows   and   Other   Livestock. 

839.  The    Relative    Cost    of    Making    Logs 

from    Small   and   Large  Timber. 

840.  Control     of     the     Pocket     Gopher     in 

California. 

343.  Cheese    Pests    and    Their    Control. 

344.  Cold    Storage   as   an    Aid   to    the   Mar- 

keting of  Plums. 

346.  Almond    Pollination. 

347.  The  Control  of  Red  Spiders  in  Decid 

nous  Orchards. 
848.   Pruning  Young  Olive  Trees. 
349.   A     Study    of    Sidedraft    and     Tractor 

Hitches. 
850.   Agriculture      in      Cut-over      Redwood 

Lands. 
853.   Bovine   Infectious   Abortion. 
354.   Results  of  Rice  Experiments  in    1922. 

857.  A     Self-mixing    Dusting    Machine    for 

Applying      Dry       Insecticides       and 
Fungicides. 

858.  Black    Measles,     Water  -Berries,     and 

Related   Vine  Troubles. 

361.  Preliminary    Yield   Tables    for    Second 

Growth   Redwood. 

362.  Dust  and  the  Tractor  Engine. 

863.  The  Pruning  of  Citrus  Trees  in   Cali- 

fornia. 

864.  Fungicidal    Dusts    for   the    Control    of 

Bunt. 
365.   Avocado  Culture  in  California. 
866.  Turkish  Tobacco  Culture,   Curing  and 

Marketing. 

367.  Methods  of  Harvesting  and  Irrigation 

in   Relation  of  Mouldy  Walnuts. 

368.  Bacterial  Decomposition  of  Olives  dur- 

ing Pickling. 

369.  Comparison     of     Woods     for     Butter 

Boxes. 

370.  Browning  of  Yellow  Newtown  Apples. 

371.  The    Relative    Cost   of    Yarding    Small 

and   Large  Timber. 

373.  Pear   Pollination. 

374.  A  Survey  of  Orchard  Practices  in  the 

Citrus    Industry  of    Southern    Cali- 
fornia. 

375.  Results   of   Rice   Experiments   at   Cor- 

tena,    1923. 

376.  Sun-Drying  and  Dehydration  of  Wal 

nuts. 

377.  The  Cold   Storage  of   Pears. 
379.  Walnut  Culture  in  California. 


BULLETINS 
No. 


380. 
382. 


385. 
386. 


387. 


389. 
390. 


391. 


392. 
393. 


395. 
396. 


397. 


399. 


400. 
401. 

402. 
404. 
405. 
406. 
407. 


408. 
409. 


410. 
411. 


412. 


414. 


415. 
416. 


417. 
418. 


419. 
420. 


421. 
422. 


423. 
424. 


425. 
426. 


427. 
428. 


429. 


Growth  of  Eucalyptus  in  California 
Plantations. 

Pumping  for  Drainage  in  the  San 
Joaquin    Valley,    California. 

Pollination    of   the    Sweet   Cherry. 

Pruning  Bearing  Deciduous  Fruit 
Trees. 

Fig  Smut. 

The  Principles  and  Practice  of  Sun- 
drying  Fruit. 

Berseem  or   Egyptian    Clover. 

Harvesting  and  Packing  Grapes  in 
California. 

Machines  for  Coating  Seed  Wheat  with 
Copper    Carbonate   Dust. 

Fruit    Juice    Concentrates. 

Crop  Sequences  at  Davis. 

Cereal  Hay  Production  in  California. 
Feeding  Trials  with  Cereal  Hay. 

Bark   Diseases   of   Citrus  Trees. 

The  Mat  Bean  (Phaseolus  aconitifo 
lius). 

Manufacture  of  Roquefort  Type  Cheese 
from    Goat's   Milk. 

Orchard  Heating  in  California. 

The  Blackberry  Mite,  the  Cause  of 
Redberry  Disease  of  the  Himalaya 
Blackberry,    and   its   Control. 

The  Utilization  of  Surplus  Plums. 

Cost  of  Work  Horses  on  California 
Farms. 

The  Codling  Moth  in  Walnuts. 

The  Dehydration  of  Prunes. 

Citrus  Culture  in  Central  California. 

Stationary  Spray  Plants  in  California. 

Yield,  Stand  and  Volume  Tables  for 
White  Fir  in  the  California  Pine 
Region. 

Alternaria  Rot  of  Lemons. 

The  Digestibility  of  Certain  Fruit  By- 
products as  Determined  for  Rumi- 
nants. 

Factors  Affecting  the  Quality  of  Fresh 
Asparagus  after  it  is  Harvested. 

Paradichlorobenzeno  as  a  Soil  Fumi- 
gant. 

A  Study  of  the  Relative  Values  of  Cer- 
tain Root  Crops  and  Salmon  Oil  as 
Sources  of  Vitamin  A  for  Poultry. 

Planting  and  Thinning  Distances  for 
Deciduous  Fruit  Trees. 

The  Tractor  on   California  Farms. 

Culture  of  the  Oriental  Persimmon 
in    California. 

Poultry  Feeding:  Principles  and 
Practice. 

A  Study  of  Various  Rations  for 
Finishing  Range  Calves  as  Baby 
Beeves. 

Economic  Aspects  of  the  Cantaloupe 
Industry. 

Rice  and  Rice  By-products  as  Feeds 
for  Fattening   Swine. 

Beef   Cattle   Feeding   Trials,    1921-24. 

Cost  of  Producing  Almonds  in  Cali- 
fornia ;  a  Progress  Report. 

Apricots  (Series  on  California  Crops 
and  Prices) . 

The  Relation  of  Rate  of  Maturity  to 
Egg  Production. 

Apple   Growing  in    California. 

Apple  Pollination  Studies  in  Cali- 
fornia. 

The  Value  of  Orange  Pulp  for  Milk 
Production. 

The  Relation  of  Maturity  of  Cali- 
fornia Plums  to  Shipping  and 
Dessert   Quality. 

Economic  Status  of  the  Grape  Industry. 


CIRCULARS 

No.  No. 

87.  Alfalfa.  259. 

117.  The    Selection    and    Cost   of    a    Small  261. 

Pumping  Plant.  262. 

127.  House   Fumigation.  263. 

129.  The  Control  of  Citrus  Insects.  264. 
136.  Melilotus    indica    as    a    Green-Manure 

Crop  for  California.  265. 

144.  Oidium    or    Powdery    Mildew    of    the  266. 

Vine. 

157.  Control  of  the  Pear  Scab.  267. 
164.   Small  Fruit  Culture  in  California. 

166.  The  County   Farm  Bureau.  269. 

170.  Fertilizing     California     Soils     for     the  270. 

1918   Crop.  272. 
173.  The    Construction    of   the   Wood-Hoop 

Silo.  273. 

178.  The   Packing  of  Apples  in   California.  276. 

179.  Factors    of    Importance   in    Producing  277. 

Milk   of  Low  Bacterial   Count. 

202.  County    Organizations   for   Rural    Fire  278. 

Control. 

203.  Peat   as   a   Manure   Substitute.  279. 
209.   The  Function  of  the  Farm  Bureau. 

212.   Salvaging    Rain-Damaged    Prunes.  281. 
215.    Feeding  Dairy  Cows  in  California. 
217.   Methods   for   Marketing   Vegetables   in 

California.  282. 

230.  Testing  Milk,    Cream,    and    Skim   Milk 

for  Butterfat.  283. 

231.  The    Home    Vineyard.  284. 

232.  Harvesting    and    Handling    California  285. 

Cherries    for    Eastern    Shipment.  286. 

234.   Winter  Injury  to  Young  Walnut  Trees  287. 

during  1921-22.  288. 

238.  The  Apricot  in   California.  289. 

239.  Harvesting     and     Handling     Apricots  290. 

and  Plums  for  Eastern  Shipment.  291. 

240.  Harvesting    and    Handling    Pears    for 

Eastern   Shipment.  292. 

241.  Harvesting  and  Handling  Peaches  for  293. 

Eastern   Shipment.  294. 

243.  Marmalade  Juice  and  Jelly  Juice  from  295. 

Citrus  Fruits. 

244.  Central  Wire  Bracing  for  Fruit  Trees.  296. 

245.  Vine   Pruning   Systems. 

248.  Some    Common    Errors    in    Vine  Prun-  298. 

kig  and  Their  Remedies. 

249.  Replacing    Missing    Vines.  300. 

250.  Measurement   of   Irrigation    Water   on  301. 

the  Farm.  302. 

252.  Supports  for  Vines.  303. 

253.  Vineyard  Plans. 

254.  The  Use  of  Artificial  Light  to  Increase  304. 

Winter   Egg   Production.  305. 

255.  Leguminous  Plants  as  Organic  Fertil-  306. 

izer   in    California    Agriculture. 

256.  The   Control   of  Wild    Morning   Glory.  307. 

257.  The  Small-Seeded  Horse  Bean.  308. 

258.  Thinning   Deciduous    Fruits.  309. 


Pear  By-products. 

Sewing  Grain  Sacks. 

Cabbage  Growing  in  California. 

Tomato  Production  in  California. 

Preliminary      Essentials      to      Bovine 

Tuberculosis  Control. 
Plant  Disease  and   Pest  Control. 
Analyzing     the     Citrus     Orchard     by 

Means  of   Simple  Tree   Records. 
The  Tendency  of  Tractors  to  Rise  in 

Front;    Causes  and  Remedies. 
An  Orchard  Brush  Burner. 
A  Farm  Septic  Tank. 
California  Farm  Tenancy  and  Methods 

of  Leasing. 
Saving  the  Gophered  Citrus  Tree. 
Home  Canning. 
Head,   Cane,    and   Cordon   Pruning  of 

Vines. 
Olive  Pickling  in  Mediterranean  Coun- 
tries. 
The  Preparation  and  Refining  of  Olive 

Oil   in    Southern    Europe. 
The  Results  of  a  Survey  to  Determine 

the  Cost  of  Producing  Beef  in  Cali- 
fornia. 
Prevention  of  Insect  Attack  on  Stored 

Grain. 
Fertilizing  Citrus  Trees  in   California. 
The   Almond   in   California. 
Sweet  Potato  Production  in  California. 
Milk  Houses  for  California  Dairies. 
Potato   Production   in    California. 
Phylloxera   Resistant  Vineyards. 
Oak  Fungus  in  Orchard  Trees. 
The  Tangier  Pea. 
Blackhead   and   Other   Causes  of  Loss 

of  Turkeys  in   California. 
Alkali  Soils. 

The    Basis   of   Grape    Standardization. 
Propagation   of   Deciduous   Fruits. 
The   Growing   and   Handling  of   Head 

Lettuce  in   California. 
Control     of     the     California     Ground 

Squirrel. 
The    Possibilities    and    Limitations    of 

Cooperative  Marketing. 
Coccidiosis  of  Chickens. 
Buckeye  Poisoning  of  the  Honey  Bee. 
The   Sugar  Beet  in   California. 
A  Promising  Remedy  for  Black  Measles 

of  the  Vine. 
Drainage  on  the  Farm. 
Liming  the  Soil. 
A  General  Purpose  Soil  Auger  and  its 

Use  on  the  Farm. 
American   Foulbrood   and  its   Control. 
Cantaloupe  Production  in   California. 
Fruit  Tree  and  Orchard  Judging. 


The  publications  listed  above  may  be  had  by  addressing 

College  of  Agriculture, 

University  of  California, 

Berkeley,  California. 


12m-3,'28 


